NO-ISSUE fix: if expression

.gitea/workflows/pr-title-check.yaml

@@ -1,5 +1,11 @@
 name: PR Title Check
-on: [pull_request]
+on:
+  pull_request:
+    types:
+      - opened
+      - edited
+      - synchronize
+      - reopened
 
 jobs:
   pr-title-check:
@@ -10,8 +16,8 @@ jobs:
 
       - name: Check PR title
         run: |
-          title=${{ gitea.event.pull_request.title }}
+          title="${{ gitea.event.pull_request.title }}"
-          if [[ ! $title =~ ^(BLOG-[0-9]+|NO-ISSUE) [A-Z].+$ ]]; then
+          if [[ ! "$title" =~ "^(BLOG-[0-9]+|NO-ISSUE) [A-Z].+$" ]]; then
             echo 'The title is not meet the format `BLOG-XXX Title title title`'
             exit 1
           else