change ophyd_async to version 0.21.1

[srishtysajeev]

This is to fix dependency issues in the blueapi pod. The previous syntax "ophyd_async @ git+https://github.com/bluesky/ophyd-async.git" is pointing to a non existent tag of ophyd-async (0.21.2).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 16.66%. Comparing base (b72c6a9) to head (22cb603).

Additional details and impacted files

@@            Coverage Diff             @@
##            main      #21       +/-   ##
==========================================
+ Coverage   2.59%   16.66%   +14.06%     
==========================================
  Files          6        2        -4     
  Lines         77       12       -65     
==========================================
  Hits           2        2               
+ Misses        75       10       -65     

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[srishtysajeev]

Looks alright.