2nd attempt at Python 3.9 support

[jGaboardi]

Addressing #40.

[codecov]

Codecov Report

Merging #41 (ebb3cb2) into main (dc77dca) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff          @@
##            main     #41   +/-   ##
=====================================
  Coverage   84.8%   84.9%           
=====================================
  Files          5       5           
  Lines       1201    1203    +2     
  Branches     302     304    +2     
=====================================
+ Hits        1019    1021    +2     
  Misses       117     117           
  Partials      65      65           

Impacted Files	Coverage Δ
tigernet/utils.py	79.5% <100.0%> (+0.1%)	⬆️