Fixed: Memleak in Repository_config__get__()

There was a memleak because of a missing Py_INCREF() for self->config. We need 2 Py_INCREF() here
because one is returned and one is kept internally. Thanks @delanne for reporting and providing
the patch.

src/repository.c

@@ -497,6 +497,9 @@ Repository_config__get__(Repository *self)
 
         py_config->config = config;
         self->config = (PyObject*)py_config;
+        // We need 2 refs here.
+        // One is returned, one is keep internally.
+        Py_INCREF(self->config);
     } else {
         Py_INCREF(self->config);
     }