test: fix bad binary pattern

lib-ee/emqx_ee_bridge/test/emqx_bridge_impl_kafka_producer_SUITE.erl

@@ -383,7 +383,7 @@ config(Args) ->
         #{atom_key => true}
     ),
     InstId = maps:get("instance_id", Args),
-    <<"bridge:", BridgeId>> = InstId,
+    <<"bridge:", BridgeId/binary>> = InstId,
     Parsed#{bridge_name => erlang:element(2, emqx_bridge_resource:parse_bridge_id(BridgeId))}.
 
 hocon_config(Args) ->