Core:detect_github_repo_move_core error on repos that have been deleted

> [!NOTE]
> Migrated from [augurlabs/augur#3166](https://github.com/augurlabs/augur/issues/3166)
> Originally opened by `@cdolfi` on 2025-06-03

---

Error handling needed for repositories that have been deleted

Example: https://github.com/anaconda-platform/transformers-feedstock

`Exception('ERROR: Repo has moved, and there is no redirection! 404 returned, not 301. Resetting Collection!')`

```
Traceback (most recent call last):
File "/opt/venv/lib/python3.9/site-packages/celery/app/trace.py", line 451, in trace_task
R = retval = fun(*args, **kwargs)
File "/opt/venv/lib/python3.9/site-packages/celery/app/trace.py", line 734, in __protected_call__
return self.run(*args, **kwargs)
File "/augur/augur/tasks/github/detect_move/tasks.py", line 27, in detect_github_repo_move_core
ping_github_for_repo_move(session, key_auth, repo, logger)
File "/augur/augur/tasks/github/detect_move/core.py", line 118, in ping_github_for_repo_move
raise Exception("ERROR: Repo has moved, and there is no redirection! 404 returned, not 301. Resetting Collection!")
Exception: ERROR: Repo has moved, and there is no redirection! 404 returned, not 301. Resetting Collection!

```