minor #14943 [Messenger] [CS] Add missing comma in PHP configuration (sebpacz)

This PR was merged into the 5.2 branch.

Discussion
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[Messenger] [CS] Add missing comma in PHP configuration

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eee0223 [Messenger][CS] Add missing comma in PHP configuration

Author: OskarStark

messenger.rst

@@ -899,7 +899,7 @@ options. Options can be passed to the transport via a DSN string or configuratio
                         'dsn' => '%env(MESSENGER_TRANSPORT_DSN)%',
                         'options' => [
                             'auto_setup' => false,
-                        ]
+                        ],
                     ],
                 ],
             ],