Add max paramter to membership list

By default, keycloak has:

Query param max: Maximum results size (defaults to 100)

util/keycloak_client.py

@@ -152,7 +152,7 @@ def get_project_members(self, charge_code):
             url=keycloakproject._client.get_full_url(
                 keycloakproject.get_path("collection", realm=self.realm_name)
             )
-            + "/{id}/members".format(id=group["id"]),
+            + "/{id}/members?max=9999".format(id=group["id"]),
         )
         return [m["username"] for m in members]