Merge pull request #2966 from k8s-infra-cherrypick-robot/cherry-pick-2964-to-release-0.18

[release-0.18] 🌱 pr-verify: use env var for passing the PR title

Author: k8s-ci-robot

Diff for: .github/workflows/verify.yml

@@ -15,4 +15,4 @@ jobs:
         env:
           PR_TITLE: ${{ github.event.pull_request.title }}
         run: |
-          ./hack/verify-pr-title.sh "${{ github.event.pull_request.title }}"
+          ./hack/verify-pr-title.sh "${PR_TITLE}"