Update tox.ini

[telegraphic]

Should fix failing tests: since tox 4, passenv is a comma-separated list of environment variables (it used to be a space-separated list)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (cbcebec) to head (2a54eac).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #182   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           12        12           
  Lines         1088      1093    +5     
=========================================
+ Hits          1088      1093    +5     

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[telegraphic]

• Tests running on python versions ['3.7', '3.8', '3.9', '3.10', '3.11'] (removed 3.5 and 3.6)
• Fixed failing test in test_01_hickle_helpers.py, due to h5py change of OSError to KeyError
• Removed x86 tests and added with arm64 tests for Mac (3.10 onwards)
• Removed astropy version pin