Ignore some lines for coverage

[dstansby]

We (well, I) have been a bit sloppy with code coverage recently. This ignores a couple of lines that aren't covered in tests, but don't need to be.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.71%. Comparing base (29995e3) to head (bf2a6e8).
Report is 42 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #633      +/-   ##
==========================================
- Coverage   99.81%   96.71%   -3.11%     
==========================================
  Files          62       62              
  Lines        2712     2708       -4     
==========================================
- Hits         2707     2619      -88     
- Misses          5       89      +84     

Files with missing lines	Coverage Δ
numcodecs/checksum32.py	100.00% <ø> (+1.13%)	⬆️
numcodecs/tests/test_zarr3.py	96.66% <100.00%> (-1.16%)	⬇️

... and 4 files with indirect coverage changes

[jakirkham]

Thanks David! 🙏

Had a couple questions below

[jakirkham]

Thanks David! 🙏