Use Optional for param

sygnal/gcmpushkin.py

@@ -196,7 +196,7 @@ def __init__(self, name: str, sygnal: "Sygnal", config: Dict[str, Any]) -> None:
                 "Config field fcm_options, if set, must be a dictionary of options"
             )
 
-    def _load_credentials(self, proxy_url: str | None) -> None:
+    def _load_credentials(self, proxy_url: Optional[str]) -> None:
         self.credentials: Optional[Credentials] = None
 
         if self.api_version is APIVersion.V1:

tests/test_gcm.py

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import json
-from typing import TYPE_CHECKING, Any, AnyStr, Dict, List, Tuple
+from typing import TYPE_CHECKING, Any, AnyStr, Dict, List, Optional, Tuple
 from unittest.mock import MagicMock
 
 from sygnal.gcmpushkin import APIVersion, GcmPushkin
@@ -117,7 +117,7 @@ def preload_with_response(
         self.preloaded_response = DummyResponse(code)
         self.preloaded_response_payload = response_payload
 
-    def _load_credentials(self, proxy_url: str | None) -> None:
+    def _load_credentials(self, proxy_url: Optional[str]) -> None:
         if self.api_version is APIVersion.V1:
             self.credentials = TestCredentials()  # type: ignore[assignment]
             self.google_auth_request = None  # type: ignore[assignment]