Fix py 3.6 multi inheritance issue

Author: ro-oliveira95

src/oop_ext/interface/_tests/test_interface.py

@@ -1085,7 +1085,7 @@ def testGenericInterface() -> None:
 
     T = TypeVar("T", covariant=True)
 
-    class IFoo(Interface, Generic[T], TypeCheckingSupport):
+    class IFoo(Generic[T], Interface, TypeCheckingSupport):
         def GetOutput(self) -> T:  # type:ignore[empty-body]
             ...