Run tests through Miri on CI

[macladson]

Addresses #65

Additionally run our CI tests through the Miri interpreter to check for undefined behaviour.
This will be helpful in ensuring our safety assumptions about #55 are correct.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.92%. Comparing base (6aee870) to head (8b0078e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #70   +/-   ##
=======================================
  Coverage   58.92%   58.92%           
=======================================
  Files           8        8           
  Lines         297      297           
=======================================
  Hits          175      175           
  Misses        122      122           

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[michaelsproul]

Heck yeah!