Allow push commits that are not part of pr

I hope

.github/workflows/build_nix.yml

@@ -35,5 +35,5 @@ jobs:
       - name: Building package
         run: nix build .#packages.${{ matrix.system }}.default
       - name: Push result to cache
-        if: ${{ github.event.pull_request.head.repo.full_name == 'MoonVision/jira-tools' }}
+        if: "! github.event.pull_request.head.repo.fork " 
         run: nix run nixpkgs#attic-client push moonvision-foss result