💚 try to fix forgejo builds

It happens to be that forgejo is not cleaning up it's cache when doing scheduled runs.

.forgejo/workflows/nix_build.yaml

@@ -10,6 +10,8 @@ jobs:
     runs-on: native
     steps:
       - uses: actions/checkout@v4
+        with:
+          clean: true
       - name: update nix flakes
         if: ${{ github.event_name == 'schedule' }}
         # we need to use our ssh key here because we need access to private flakes