io conflicts with builtin

[tjlane]

Ruff was (rightfully) complaining that meteor.io could parrot the io builtin. So, simply rename meteor/io.py to mtzio.py.

I further cleared a warning regarding outdated ruff rules, and changed one line in test_scale.py that mypy was complaining about. This allows the PR to pass.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.62%. Comparing base (8769c2f) to head (fc5720b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #97   +/-   ##
=======================================
  Coverage   95.62%   95.62%           
=======================================
  Files          15       15           
  Lines         938      938           
=======================================
  Hits          897      897           
  Misses         41       41           

Flag	Coverage Δ
unittests	95.62% <100.00%> (ø)

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[kmdalton]

This looks to be uncontentious and safe to me! Now I feel like I have to rename all the io submodules in all my programs 😮‍💨.