Also update on PHP 7.4

Author: dmolineus

.github/workflows/diagnostics.yml

@@ -18,7 +18,7 @@ jobs:
       matrix:
         include:
           - php: '7.4'
-            phpcq_install: 'install'
+            phpcq_install: 'update'
             phpcq_flags: ''
           - php: '8.0'
             phpcq_install: 'update'