fix mypy errors: use Optional for None default arguments

Author: EhteshamSid

samcli/lib/sync/infra_sync_executor.py

@@ -72,7 +72,7 @@ class InfraSyncResult:
     _infra_sync_executed: bool
     _code_sync_resources: Set[ResourceIdentifier]
 
-    def __init__(self, executed: bool, code_sync_resources: Set[ResourceIdentifier] = None) -> None:
+    def __init__(self, executed: bool, code_sync_resources: Optional[Set[ResourceIdentifier]] = None) -> None:
         """
         Constructor
 

tests/integration/durable_integ_base.py

@@ -142,7 +142,7 @@ def log_output():
     def assert_invoke_output(
         self,
         stdout: str,
-        input_data: Dict[str, Any] = None,
+        input_data: Optional[Dict[str, Any]] = None,
         execution_name: Optional[str] = None,
         expected_status: str = "SUCCEEDED",
     ) -> str: