Fix broken tests due to pytest-asyncio update

[DominicOram]

Fixes broken tests, issue was pytest-dev/pytest-asyncio#1106

Instructions to reviewer on how to test:

1. Reinstall the dev environement
2. Confirm tests pass on this branch but fail on main

Checks for reviewer

• Would the PR title make sense to a scientist on a set of release notes
• If a new device has been added does it follow the standards
• If changing the API for a pre-existing device, ensure that any beamlines using this device have updated their Bluesky plans accordingly
• Have the connection tests for the relevant beamline(s) been run via dodal connect ${BEAMLINE}

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.97%. Comparing base (483b93d) to head (fdbb87f).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1246   +/-   ##
=======================================
  Coverage   97.97%   97.97%           
=======================================
  Files         199      199           
  Lines        7673     7673           
=======================================
  Hits         7518     7518           
  Misses        155      155           

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