implement support for forgejo prs

[olamidepeterojo]

TODO:

• [x] Write new tests or update the old ones to cover new functionality.
• [ ] Update doc-strings where appropriate.
• [ ] Update or write new documentation in packit/packit.dev.
• [ ] ‹fill in›

Fixes #879

Related to

Merge before/after

RELEASE NOTES BEGIN

Packit now supports automatic ordering of ☕ after all checks pass.

RELEASE NOTES END

[softwarefactory-project-zuul[bot]]

Build failed. https://softwarefactory-project.io/zuul/t/packit-service/buildset/c938c52c13644eb489fc02039854a80e

:heavy_check_mark: pre-commit SUCCESS in 2m 34s :x: ogr-tests-pip-deps FAILURE in 2m 06s

[lbarcziova]

hi and thanks for the effort on this issue! Considering this has become a priority for us, I'm currently working on the implementation. You can check my progress in #925, feel free to suggest any improvements.