Add return type

Co-authored-by: Kim Gustyr <[email protected]>

src/edge_proxy/server.py

@@ -96,7 +96,7 @@ async def identity(
 async def get_identities(
     identifier: str,
     x_environment_key: str = Header(None),
-):
+) -> ORJSONResponse:
     data = environment_service.get_identity_response_data(
         IdentityWithTraits(identifier=identifier), x_environment_key
     )