Fix typo in event.py

Author: syeeuns

pymysqlreplication/event.py

@@ -314,7 +314,7 @@ def _read_status_vars_value_for_key(self, key):
             """
             mts_accessed_dbs < 254:
                 `mts_accessed_dbs` is equal to the number of dbs
-                acessed by the query event.
+                accessed by the query event.
             mts_accessed_dbs == 254:
                 This is the case where the number of dbs accessed
                 is 1 and the name of the only db is ""