clarify types

Author: khvn26

api/integrations/launch_darkly/exceptions.py

@@ -8,6 +8,6 @@ class LaunchDarklyAPIError(Exception):
 class LaunchDarklyRateLimitError(LaunchDarklyAPIError):
     """Exception raised when the LaunchDarkly API rate limit is exceeded."""
 
-    def __init__(self, retry_at: datetime | None = None):
+    def __init__(self, retry_at: datetime):
         super().__init__()
         self.retry_at = retry_at