Adjust `codecov.yml`

[ddabble]

Proposed changes

codecov.yml has not been substantially updated in 5+ years (last time was d676a74060df5b3eb04817554b51112b9b144313), so these changed settings seem more sensible.

For reference, most default values are listed here: https://docs.codecov.com/docs/codecovyml-reference

Areas to review closely

None in particular.

Checklist

(If any of the points are not relevant, mark them as checked)

• [x] Created tests that fail without the changes, if relevant/possible
• [x] Made sure that your code conforms to the code style guides and that any common code smells have been addressed
  • (It's not intended that you read through this whole document, but that you get yourself an overview over its contents, and that you keep it in mind while taking a second look at your code before opening a pull request)
• [x] Added sufficient documentation - e.g. as docstrings or in the README, if suitable
• [x] Added your changes to the "Unreleased" section of the changelog - mainly the changes that are of particular interest to users and/or developers, if any
• [x] Added a "Deployment notes" section above, if anything out of the ordinary should be done when deploying these changes to the server

[codecov[bot]]

Codecov Report

Merging #619 (61ffcbb) into dev (4eab8d7) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #619   +/-   ##
=======================================
  Coverage   87.70%   87.70%           
=======================================
  Files         134      134           
  Lines        5644     5644           
=======================================
  Hits         4950     4950           
  Misses        694      694