ci: Disable "validate pull request" workflow for release pull requests (#3346)

The "validate pull request" workflow checks if the pull request title
matches the conventional commits syntax. Unfortunately "release:
version" doesn't seem to be considered as valid, so instead, we should
disable the check for release pull requests.

Author: Mrtenz

.github/workflows/validate-pull-request.yml

@@ -13,6 +13,7 @@ jobs:
   validate-pull-request-title:
     name: Validate title
     runs-on: ubuntu-latest
+    if: ${{ !startsWith(github.head_ref , 'release/') }}
     steps:
       - name: Validate title
         # `amannn/[email protected]`