Set up pre-commit for managing the linters

[mcflugen]

This pull request adds a pre-commit config file that holds the linters for deltametrics, and adds a new job, lint, to the GitHub Actions workflow. The lint nox session doesn't run any of the pre-commit hooks, I'll add that in separate pull requests.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.32%. Comparing base (a298e55) to head (26ccdce).
Report is 5 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #183   +/-   ##
========================================
  Coverage    89.32%   89.32%           
========================================
  Files            9        9           
  Lines         3617     3617           
========================================
  Hits          3231     3231           
  Misses         386      386           

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