Trying to build psi4 with CMake 4.0 we get a build failure of
```
[ 22%] Performing download step (download, verify and extract) for 'chemps2_external'
cd /builddir/build/BUILD/psi4-1.9.1-build/psi4-1.9.1/redhat-linux-build/external/upstream/chemps2/chemps2_external-prefix/src && /usr/bin/cmake -DCMAKE_MESSAGE_LOG_LEVEL=VERBOSE -P /builddir/build/BUILD/psi4-1.9.1-build/psi4-1.9.1/redhat-linux-build/external/upstream/chemps2/chemps2_external-prefix/src/chemps2_external-stamp/download-chemps2_external.cmake
-- Downloading...
   dst='/builddir/build/BUILD/psi4-1.9.1-build/psi4-1.9.1/redhat-linux-build/external/upstream/chemps2/chemps2_external-prefix/src/d8ac508.tar.gz'
   timeout='none'
   inactivity timeout='none'
-- Using src='https://github.com/SebWouters/CheMPS2/archive/d8ac508.tar.gz'
-- Retrying...
-- Using src='https://github.com/SebWouters/CheMPS2/archive/d8ac508.tar.gz'
-- Retry after 5 seconds (attempt #2) ...
-- Using src='https://github.com/SebWouters/CheMPS2/archive/d8ac508.tar.gz'
-- Retry after 5 seconds (attempt #3) ...
-- Using src='https://github.com/SebWouters/CheMPS2/archive/d8ac508.tar.gz'
-- Retry after 15 seconds (attempt #4) ...
-- Using src='https://github.com/SebWouters/CheMPS2/archive/d8ac508.tar.gz'
-- Retry after 60 seconds (attempt #5) ...
-- Using src='https://github.com/SebWouters/CheMPS2/archive/d8ac508.tar.gz'
CMake Error at chemps2_external-stamp/download-chemps2_external.cmake:163 (message):
  Each download failed!

    error: downloading 'https://github.com/SebWouters/CheMPS2/archive/d8ac508.tar.gz' failed
          status_code: 6
          status_string: "Could not resolve hostname"
          log:
          --- LOG BEGIN ---
          Could not resolve host: github.com

  shutting down connection #0
```

This is rather odd since the ExternalProject calls should have been overwritten.

Reproducible: Always