Clean up temporary files

[AdamOrmondroyd]

Description

Pytest provides a handy tmp_path and apparently cleans up files placed in there.

Fixes #373

Checklist:

• I have performed a self-review of my own code
• My code is PEP8 compliant (flake8 anesthetic tests)
• My code contains compliant docstrings (pydocstyle --convention=numpy anesthetic)
• New and existing unit tests pass locally with my changes (python -m pytest)
• I have added tests that prove my fix is effective or that my feature works
• I have appropriately incremented the semantic version number in both README.rst and anesthetic/_version.py

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (cb60b9a) to head (023e52c).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #374   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           36        36           
  Lines         3032      3032           
=========================================
  Hits          3032      3032           

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[AdamOrmondroyd]

There's something funky going on with macos and pytables, had to try three times to get the runner to complete. Whatever the problem is, it isn't one to fix here

Issue at PyTables/PyTables#1114

[williamjameshandley]

I like this a lot. Nice work.