Merge branch '6.4' into 7.0

* 6.4:
  [Scheduler] Emphasize `__toString()`

Author: javiereguiluz

scheduler.rst

@@ -182,6 +182,8 @@ For example, if you want to send customer reports daily except for holiday perio
         {
         }
 
+        // use this method to give a nice displayable name to
+        // identify your trigger (it eases debugging)
         public function __toString(): string
         {
             return $this->inner.' (except holidays)';