Description of problem:
libplacebo-devel doesn't install on EPEL9 because nothing provides pkgconfig(shaderc) >= 2019.1

Version-Release number of selected component (if applicable):
libplacebo-devel-4.157.0-1.el9

Steps to Reproduce:
1. sudo dnf -y install libplacebo-devel

Actual results:
...
 Problem: conflicting requests
  nothing provides pkgconfig(shaderc) >= 2019.1 needed by libplacebo-devel-4.157.0-1.el9.x86_64

Additional info:

Another thing that I noticed is that the source package doesn't build anymore.

To solve this you would need to ask for the package to be added to the CRB repository[0]. There is already a request for that (BZ2076578), so i'll link this bug report to that request.

This problem was found using the following service:
https://tdawson.fedorapeople.org/epel/willit/epel9/status-wont-install.html

[0] https://docs.fedoraproject.org/en-US/epel/epel-policy-missing-sub-packages/#missing_built_sub-packages