Handle Issues without Events

[sgoggins]

dev branch:

Issues can exist without event streams as noted by this error.

Traceback (most recent call last):
  File "/home/ubuntu/github/virtualenvs/hosted/lib/python3.11/site-packages/celery/app/trace.py", line 451, in trace_task
    R = retval = fun(*args, **kwargs)
                 ^^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/virtualenvs/hosted/lib/python3.11/site-packages/celery/app/trace.py", line 734, in __protected_call__
    return self.run(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/augur/augur/tasks/github/events.py", line 39, in collect_events
    for event in event_generator:
  File "/home/ubuntu/github/augur/augur/tasks/github/events.py", line 103, in collect_pr_and_issues_events_by_number
    yield from github_data_access.paginate_resource(event_url)
  File "/home/ubuntu/github/augur/augur/tasks/github/util/github_data_access.py", line 44, in paginate_resource
    response = self.make_request_with_retries(url)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/augur/augur/tasks/github/util/github_data_access.py", line 114, in make_request_with_retries
    return self.__make_request_with_retries(url, method, timeout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/virtualenvs/hosted/lib/python3.11/site-packages/tenacity/__init__.py", line 330, in wrapped_f
    return self(f, *args, **kw)
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/virtualenvs/hosted/lib/python3.11/site-packages/tenacity/__init__.py", line 467, in __call__
    do = self.iter(retry_state=retry_state)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/virtualenvs/hosted/lib/python3.11/site-packages/tenacity/__init__.py", line 368, in iter
    result = action(retry_state)
             ^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/virtualenvs/hosted/lib/python3.11/site-packages/tenacity/__init__.py", line 390, in <lambda>
    self._add_action_func(lambda rs: rs.outcome.result())
                                     ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/concurrent/futures/_base.py", line 449, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/concurrent/futures/_base.py", line 401, in __get_result
    raise self._exception
  File "/home/ubuntu/github/virtualenvs/hosted/lib/python3.11/site-packages/tenacity/__init__.py", line 470, in __call__
    result = fn(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/augur/augur/tasks/github/util/github_data_access.py", line 128, in __make_request_with_retries
    return self.make_request(url, method, timeout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/github/augur/augur/tasks/github/util/github_data_access.py", line 102, in make_request
    raise UrlNotFoundException(f"Could not find {url}")
augur.tasks.github.util.github_data_access.UrlNotFoundException: Could not find https://api.github.com/repos/azure/resourcemodules/issues/2857/events