Pin auto-assign workflow action to v4

Author: pboling

.github/workflows/auto-assign.yml

@@ -12,7 +12,7 @@ jobs:
       pull-requests: write
     steps:
     - name: 'Auto-assign issue'
-      uses: pozil/auto-assign-issue@v2
+      uses: pozil/auto-assign-issue@07fe6dc0e9771842b428f5739098d6140734e226 # v4
       with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           assignees: pboling