Update test-phpunit.yml

Author: NielBuys

.github/workflows/test-phpunit.yml

@@ -5,7 +5,7 @@ on: [push, pull_request]
 jobs:
   tests:
     runs-on: ubuntu-latest
-    if: '!contains(github.event.head_commit.message, "[ci skip]")'
+    if: "!contains(github.event.head_commit.message, '[ci skip]')"
     env:
       PHP_INI_VALUES: assert.exception=1, zend.assertions=1