Replace deprecated kubebuilder-release-tools PR verifier with inline scripts (#210)

Signed-off-by: Zhiwei Yin <zyin@redhat.com>

Author: zhiweiyin318

.github/workflows/pr-verify.yml

@@ -1,11 +1,7 @@
 name: PR Verifier
 
 on:
-  # NB: using `pull_request_target` runs this in the context of
-  # the base repository, so it has permission to upload to the checks API.
-  # This means changes won't kick in to this file until merged onto the
-  # main branch.
-  pull_request_target:
+  pull_request:
     types: [opened, edited, reopened, synchronize]
 
 jobs:
@@ -17,7 +13,25 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Verifier action
-        id: verifier
-        uses: kubernetes-sigs/kubebuilder-release-tools@v0.3.0
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
+        env:
+          TITLE: ${{ github.event.pull_request.title }}
+        run: |
+          if [[ -z "$TITLE" ]]; then
+            echo "Error: PR title cannot be empty."
+            exit 1
+          fi
+
+          if ! [[ "$TITLE" =~ ^(:sparkles:|:bug:|:book:|:memo:|:warning:|:seedling:|:question:|$'\u2728'|$'\U0001F41B'|$'\U0001F4D6'|$'\U0001F4DD'|$'\u26A0'$'\uFE0F'?|$'\U0001F331'|$'\u2753') ]]; then
+            echo "Error: Invalid PR title format."
+            echo "Your PR title must start with one of the following indicators:"
+            echo "- :sparkles: ✨ feature"
+            echo "- :bug: 🐛 bug fix"
+            echo "- :book: 📖 docs"
+            echo "- :memo: 📝 proposal"
+            echo "- :warning: ⚠️ breaking change"
+            echo "- :seedling: 🌱 other/misc"
+            echo "- :question: ❓ requires manual review"
+            exit 1
+          fi
+
+          echo "PR title is valid: '$TITLE'"