Drop Fedora 36 and add Fedora 39 to the test suite

[yubiuser]

What does this PR aim to accomplish?:

Fedora 36 is EOL since May 2023 and today they shut down the metadata for repository for 'fedora-modular'. Our test suite will therefor always fail.
Fedora 39 was released today.

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[yubiuser]

Tests will fail until someone with write access adds Fedora 39 to dev_supporedos.yaml

[yubiuser]

@pi-hole/core-maintainers

Fedora 36 tests are failing again for various core PRs. Any opinions about this PR?

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/v6-beta-qol-improvements/67308/2

[PromoFaux]

Fedora 37 now EOL, too. Do you want to address that in this PR? I'll update the dev TXT record

[yubiuser]

I also removed Fedora 37

[yubiuser]

Doc PR: pi-hole/docs#989