Expand PHP version matrix in CI workflow

Author: overtrue

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
   phpunit:
     strategy:
       matrix:
-        php_version: [8.1, 8.2]
+        php_version: [8.1, 8.2, 8.3, 8.4, 8.5]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2