Supporting 3.12 and Dropping py26 py36 support

[jmvrbanac]

Addresses #113

[codecov]

Codecov Report

Attention: Patch coverage is 7.93037% with 476 lines in your changes missing coverage. Please review.

Please upload report for BASE (master@1f5a729). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
specter/vendor/ast_decompiler.py	4.03%	466 Missing and 10 partials ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #114   +/-   ##
=========================================
  Coverage          ?   59.90%           
=========================================
  Files             ?       15           
  Lines             ?     2115           
  Branches          ?      290           
=========================================
  Hits              ?     1267           
  Misses            ?      788           
  Partials          ?       60           

Files with missing lines	Coverage Δ
specter/expect.py	93.82% <100.00%> (ø)
specter/reporting/__init__.py	94.73% <100.00%> (ø)
specter/reporting/utils.py	79.41% <100.00%> (ø)
specter/reporting/xunit.py	97.36% <100.00%> (ø)
specter/spec.py	96.19% <100.00%> (ø)
specter/util.py	90.74% <100.00%> (ø)
specter/vendor/ast_decompiler.py	6.00% <4.03%> (ø)

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