Update build-openwrt.yml

Author: hubbylei

.github/workflows/build-openwrt.yml

@@ -181,7 +181,7 @@ jobs:
       uses: dev-drprasad/delete-older-releases@master
       if: steps.compile.outputs.status == 'success' && !cancelled()
       with:
-        keep_latest: 10
+        keep_latest: 12
         delete_tags: true
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}