gh-37073: `build/pkgs/free_fonts`: Fix fedora system package information
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The package `gnu-free-fonts` does not exist, as seen for example in
- `fedora-36-maximal` (https://github.com/sagemath/sage/actions/runs/752
1668027/job/20497322866).
- `fedora-39-maximal` (https://github.com/sagemath/sage/actions/runs/752
1668027/job/20497323960#step:11:20270)
`gnu-free-fonts` is merely the name of the source package, the actual
rpms are called `gnu-free-mono-fonts`, `gnu-free-sans-fonts `, `gnu-
free-serif-fonts`
https://koji.fedoraproject.org/koji/buildinfo?buildID=2308657
Here we adjust for it.
According to https://rpmfind.net/linux/rpm2html/search.php?query=gnu-
free-sans-fonts, the packages are available for fedora >=37, EPEL 9,
centos-7, centos-stream-8. Accordingly we remove the setting
`IGNORE_MISSING_SYSTEM_PACKAGES=no` from fedora < 37.
Also adding fedora-40, the new rawhide.
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URL: https://github.com/sagemath/sage/pull/37073
Reported by: Matthias Köppe
Reviewer(s): Kwankyu Lee
