Start building CQ for py3.9

[adam-urbanczyk]

No description provided.

[codecov]

Codecov Report

Merging #672 (4025370) into master (dc9b0e7) will increase coverage by 0.74%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #672      +/-   ##
==========================================
+ Coverage   94.03%   94.77%   +0.74%     
==========================================
  Files          31       31              
  Lines        6642     9079    +2437     
  Branches      726     1132     +406     
==========================================
+ Hits         6246     8605    +2359     
- Misses        258      295      +37     
- Partials      138      179      +41     

Impacted Files	Coverage Δ
tests/test_cadquery.py	99.36% <0.00%> (+0.23%)	⬆️
cadquery/occ_impl/shapes.py	93.34% <0.00%> (+1.41%)	⬆️
cadquery/cq.py	91.49% <0.00%> (+1.60%)	⬆️

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[adam-urbanczyk]

We might also want to stop providing 3.6 builds

[jmwright]

@adam-urbanczyk What's the reasoning behind dropping support for Python 3.6?

[adam-urbanczyk]

PEP 563 and shorter build times.

[jmwright]

@adam-urbanczyk The comment I made is just a suggestion. This PR looks good.

[jmwright]

16.04 is going EOL next month. GitHub Actions is going to start defaulting to 20.04 for the "latest" image when this EOL is hit. It might be worth moving to 18.04 for these builds while you're at it.

https://ubuntu.com/about/release-cycle

https://phoenixnap.com/kb/ubuntu-16-04-end-of-life

[adam-urbanczyk]

OK, merging.