Ignore KeyError

Shopify UI extensions send tokens without iss key. To prevent the middleware from raising exceptions for these requests we're now ignoring missing iss key.

shopify_auth/session_tokens/middleware.py

@@ -41,6 +41,7 @@ def get_user(token):
         JWTClaimsError,
         AssertionError,
         ObjectDoesNotExist,
+        KeyError,
     ) as e:
         logging.warning(f"Login user failed: {e}.")