Issue #3214924 by catch: Increase DRUPAL_RECOMMENDED_PHP to 8.0 in Drupal 9.3 or 9.4

(cherry picked from commit 0893b9b2)

core/lib/Drupal.php

@@ -132,7 +132,7 @@ class Drupal {
    * message, but Drupal can still be installed. Used for (e.g.) PHP versions
    * that have reached their EOL or will in the near future.
    */
-  const RECOMMENDED_PHP = '7.4';
+  const RECOMMENDED_PHP = '8.0';
 
   /**
    * The currently active container object, or NULL if not initialized yet.