chore(ci): Try to push to PR head

Author: effigies

.github/workflows/pixi-lock.yml

@@ -32,4 +32,8 @@ jobs:
         run: |
           uvx datalad run -i pixi.lock -i pyproject.toml -o pixi.lock -- pixi lock
       - name: Push updated lockfile, if needed
-        run: git push
+        run: |
+          git fetch origin refs/pull/$PULL/head
+          git push origin HEAD:refs/pull/$PULL/head
+        env:
+          PULL: ${{ github.event.pull_request.number }}