ci: Add PHP 8.5 to workflow matrix

Author: Chris53897

.github/workflows/tests.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        php: ['8.3', '8.4']
+        php: ['8.3', '8.4', '8.5']
         dependency-version: [prefer-lowest, prefer-stable]
         parallel: ['', '--parallel']