Use single quotes in the if condition for job

Author: artembilan

.github/workflows/spring-backport-issue.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   backport-issue:
     runs-on: ubuntu-latest
-    if: {{ contains(github.event.head_commit.message, "Fixes: ") || contains(github.event.head_commit.message, "Closes: ") }}
+    if: {{ contains(github.event.head_commit.message, 'Fixes: ') || contains(github.event.head_commit.message, 'Closes: ') }}
     steps:
 
       - uses: actions/checkout@v4