ci: pin hmarr/auto-approve-action action to v2.4.0 (#107)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/auto-approve.yml

@@ -11,7 +11,7 @@ jobs:
       pull-requests: write
 
     steps:
-      - uses: hmarr/auto-approve-action@v2
+      - uses: hmarr/auto-approve-action@9ae347e9f84a25da76c915a406cb17cfece1716d # v2.4.0
         if: github.actor == 'dependabot[bot]' || github.actor == 'dependabot-preview[bot]' || github.actor == 'renovate[bot]'
         with:
           github-token: '${{ secrets.GITHUB_TOKEN }}'