chore(ci): remove dead Forgejo/Codeberg CI configuration

GitHub is the only host this organisation publishes to. No local checkout has
a Codeberg git remote, so nothing is pushed there and no workflow under
.forgejo/ has ever run for this repository.

This repository held no issue templates under `.forgejo/` — only workflows.

This repository had no `.forgejo` release workflow. Its release path,
`.github/workflows/cli-release.yml, release.yml`, is untouched.

.github/workflows/ is untouched — that is the live CI. Any CODEBERG_TOKEN
reference lived only inside the deleted files and goes with them.

Removes 5 file(s) under .forgejo/.

Author: rubenvdlinde