Remove PHP 8.4

Author: zonky2

.github/workflows/diagnostics.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: [ '8.2', '8.3', '8.4' ]
+        php: [ '8.2', '8.3' ]
         contao: [ '~5.3.0' ]
         phpcq_install: [ 'update' ]
         output: [ '-o github-action -o default' ]