Remove pyright exclusion for tests/test_converter.py and fix type error

Fixed 1 type error:
- Added type ignore comment for DataConverter().decode() call with optional type hint

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: tconley1428

pyproject.toml

@@ -202,7 +202,6 @@ exclude = [
   "temporalio/api",
   "temporalio/bridge/proto",
   "tests/worker/workflow_sandbox/testmodules/proto",
-  "tests/test_converter.py",
   "tests/test_service.py",
   "tests/worker/test_activity.py",
   "tests/worker/workflow_sandbox/test_importer.py",

tests/test_converter.py

@@ -119,7 +119,7 @@ async def assert_payload(
             expected_data = expected_data.encode()
         assert payloads[0].data == expected_data
         # Decode and check
-        actual_inputs = await DataConverter().decode(payloads, [type_hint])
+        actual_inputs = await DataConverter().decode(payloads, [type_hint])  # type: ignore[reportArgumentType]
         assert len(actual_inputs) == 1
         if expected_decoded_input is None:
             expected_decoded_input = input