Description of problem:
Package python-sphinx-book-theme fails to build from source in Fedora Rawhide.

Version-Release number of selected component (if applicable):
1.2.0-1.fc45

Steps to Reproduce:
koji build --scratch f45 python-sphinx-book-theme-1.2.0-1.fc45.src.rpm

Additional info:
This package is tracked by Koschei. See:
https://koschei.fedoraproject.org/package/python-sphinx-book-theme

Reproducible: Always

Actual Results:
_______________________________ test_build_book ________________________________
sphinx_build_factory = <function sphinx_build_factory.<locals>._func at 0x7fffb50af060>
file_regression = <pytest_regressions.file_regression.FileRegressionFixture object at 0x7fffb4932ba0>
    def test_build_book(sphinx_build_factory, file_regression):
        """Test building the base book template and config."""
        sphinx_build = sphinx_build_factory("base")  # type: SphinxBuild
        sphinx_build.build(assert_pass=True)
        assert (sphinx_build.outdir / "index.html").exists(), sphinx_build.outdir.glob("*")
    
        # -- Notebooks ------------------------------------------------------------
        # Check for correct kernel name
        kernels_expected = {
            "ntbk.html": "python3",
            "ntbk_octave.html": "octave",
            "ntbk_julia.html": "julia-1.4",
        }
        for filename, kernel in kernels_expected.items():
            ntbk_html = sphinx_build.html_tree("section1", filename)
            thebe_config = ntbk_html.find("script", attrs={"type": "text/x-thebe-config"})
            kernel_name = f'name: "{kernel}",'
            if kernel_name not in thebe_config.prettify():
                raise AssertionError(f"{kernel_name} not in {kernels_expected}")
    
        # -- Sidebar --------------------------------------------------------------
        index_html = sphinx_build.html_tree("index.html")
        # Navigation entries
        if sphinx_version.major >= 8:
            # Only run this regression on the latest Sphinx series to avoid duplicates.
            sidebar = index_html.find(attrs={"class": "bd-docs-nav"})
            file_regression.check(
                sidebar.prettify(),
                basename="build__sidebar-primary__nav",
                extension=".html",
                encoding="utf8",
            )
    
        # Check navbar numbering
        sidebar_ntbk = sphinx_build.html_tree("section1", "ntbk.html").find(
            "nav", attrs={"class": "bd-docs-nav"}
        )
        # Pages and sub-pages should be numbered
        assert "1. Page 1" in str(sidebar_ntbk)
        assert "3.1. Section 1 page1" in str(sidebar_ntbk)
    
        # -- Header ---------------------------------------------------------------
        header_article = sphinx_build.html_tree("section1", "ntbk.html").find(
            "div", class_="bd-header-article"
        )
    
        file_regression.check(
            header_article.prettify(),
            basename="build__header-article",
            extension=".html",
            encoding="utf8",
        )
        # Edit button should not be on page
        assert '<a class="edit-button"' not in str(index_html)
        # Title should be just text, no HTML
        assert "Index with code in title" in str(index_html)
    
        # -- Page TOC -------------------------------------------------------------
        # Test that the TOCtree is rendered properly across different title arrangements
        for page in sphinx_build.outdir.joinpath("titles").rglob("**/page-*"):
            page_html = BeautifulSoup(page.read_text("utf8"), "html.parser")
            page_toc = page_html.find("div", attrs={"class": "bd-toc"})
            if page_toc:
>               file_regression.check(
                    page_toc.prettify(),
                    basename=f"build__pagetoc--{page.with_suffix('').name}",
                    extension=".html",
                    encoding="utf8",
                )
E               AssertionError: FILES DIFFER:
E               /tmp/pytest-of-mockbuild/pytest-0/test_build_book0/build__pagetoc--page-multipletitles.html
E               /tmp/pytest-of-mockbuild/pytest-0/test_build_book0/build__pagetoc--page-multipletitles.obtained.html
E               HTML DIFF: /tmp/pytest-of-mockbuild/pytest-0/test_build_book0/build__pagetoc--page-multipletitles.obtained.diff.html
E               --- 
E               +++ 
E               @@ -7,12 +7,12 @@
E                    Contents
E                   </div>
E                   <nav aria-labelledby="pst-page-navigation-heading-2" class="page-toc" id="pst-page-toc-nav">
E               -    <ul class="visible nav section-nav flex-column">
E               +    <ul class="pst-show_toc_level nav section-nav flex-column">
E                     <li class="toc-h1 nav-item toc-entry">
E                      <a class="reference internal nav-link" href="#">
E                       4.1. A page with multiple top-level titles
E                      </a>
E               -      <ul class="visible nav section-nav flex-column">
E               +      <ul class="pst-show_toc_level nav section-nav flex-column">
E                       <li class="toc-h2 nav-item toc-entry">
E                        <a class="reference internal nav-link" href="#a-sub-heading">
E                         4.1.1. A sub-heading
E               @@ -24,7 +24,7 @@
E                      <a class="reference internal nav-link" href="#another-top-level-title">
E                       4.2. Another top-level title
E                      </a>
E               -      <ul class="visible nav section-nav flex-column">
E               +      <ul class="pst-show_toc_level nav section-nav flex-column">
E                       <li class="toc-h2 nav-item toc-entry">
E                        <a class="reference internal nav-link" href="#another-sub-heading">
E                         4.2.1. Another sub-heading