Add file pattern filter for png

.github/workflows/generate-mistica-tokens.yml

@@ -30,6 +30,7 @@ jobs:
       - name: Commit Changes
         uses: stefanzweifel/git-auto-commit-action@v4
         with:
+          file_pattern: '*.png'
           commit_message: Record screenshots automatically launched from GH action
         env:
           GITHUB_TOKEN: ${{ secrets.NOVUM_PRIVATE_REPOS }}