[RaphaelFakhri]

What was changed

terminate_activity in the client now sets request_id on TerminateActivityExecutionRequest, the same way cancel_activity, pause_activity and unpause_activity already do. Adds a unit test in tests/test_activity.py and a changelog fragment.

Why?

The client sends TerminateActivityExecution with retry=True, but without a request ID. The server fills in a new random ID for each attempt and only treats a terminate as a duplicate when the request ID matches the one it stored. If the first attempt terminates the activity and its response is lost, the retry carries a different ID, so the server returns NotFound: no running activity execution: it closed with status TERMINATED and ActivityHandle.terminate() raises even though the activity was terminated. The Go SDK sets RequestId on this request.

Checklist

1. Closes [Bug] Retried ActivityHandle.terminate() can fail after the activity is already terminated #2008

2. How was this tested:

   • New test test_terminate_activity_generates_request_id mocks the workflow service and checks that each terminate() call sends a distinct UUID4 request ID, following test_start_activity_generates_request_id. Without the source change it fails with ValueError: badly formed hexadecimal UUID string because request_id is empty. With the change it passes, and all 35 tests in tests/test_activity.py pass against a local dev server.
   • ruff check --select I, ruff format --check, pyright, basedpyright, mypy and pydocstyle pass on the changed files.

3. Any docs updates needed?
   No.