ci: remove push trigger and add lock for PRs

.github/workflows/brew-tarball.yml

@@ -1,7 +1,6 @@
 name: Generate Homebrew tarball and Release
 
 on:
-  push:
   schedule:
     - cron: "0 1 * * TUE" # Every Tuesday at 1am UTC
   merge_group:
@@ -51,13 +50,15 @@ jobs:
             ${{ steps.generate_tarball.outputs.tarball_file }}
 
       - name: Get current date
+        if: github.event_name != 'pull_request'
         id: date
         run: |
           set -x
           echo "date=$(date -u +%Y\-%m\-%d\ %H\:%M\:%S)" >> $GITHUB_OUTPUT
           echo "tag_date=$(date -u +%Y\-%m\-%d-%H-%M-%S)" >> $GITHUB_OUTPUT
 
       - name: Create Release
+        if: github.event_name != 'pull_request'
         uses: softprops/action-gh-release@c95fe1489396fe8a9eb87c0abf8aa5b2ef267fda # v2
         with:
           name: Homebrew Tarball (${{ steps.date.outputs.date }})