fix type check

Author: jnozsc

MySQLdb/connections.py

@@ -184,7 +184,7 @@ class object, used to create cursors (keyword only)
 
         super().__init__(*args, **kwargs2)
         self.cursorclass = cursorclass
-        self.encoders = {k: v for k, v in conv.items() if type(k) is not int}
+        self.encoders = {k: v for k, v in conv.items() if not isinstance(k, int)}
 
         # XXX THIS IS GARBAGE: While this is just a garbage and undocumented,
         # Django 1.11 depends on it.  And they don't fix it because