minor #20194 [Scheduler] Fix indention and single quotes for the example in A Dynamic Vision for the Messages Generated section (smoench)

This PR was submitted for the 7.1 branch but it was merged into the 6.4 branch instead.

Discussion
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[Scheduler] Fix indention and single quotes for the example in `A Dynamic Vision for the Messages Generated` section

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Commits
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5b4c2cd [Scheduler] Fix indention and single quotes for `A Dynamic Vision for the Messages Generated` section example

Author: javiereguiluz

scheduler.rst

@@ -412,9 +412,10 @@ checks for messages to be generated::
                         new ExcludeHolidaysTrigger(
                             CronExpressionTrigger::fromSpec('@daily'),
                         ),
-                    // instead of being static as in the previous example
-                    new CallbackMessageProvider([$this, 'generateReports'], 'foo')),
-                    RecurringMessage::cron(‘3 8 * * 1’, new CleanUpOldSalesReport())
+                        // instead of being static as in the previous example
+                        new CallbackMessageProvider([$this, 'generateReports'], 'foo')
+                    ),
+                    RecurringMessage::cron('3 8 * * 1', new CleanUpOldSalesReport())
                 );
         }