Drop support for EOL Python <= 3.6

[hugovk]

Also move testing from Travis CI to GitHub Actions

• also allows testing on macOS and Windows
• 20 parallel jobs instead of 4
• Travis CI has an uncertain OSS future
• For example: https://github.com/hugovk/isodate/actions/runs/775454949

Move coverage from Coveralls to Codecov

• For example: https://app.codecov.io/gh/hugovk/isodate/

Run Flake8 via pre-commit

• Pins versions
• Makes it easy to run on CI and as optional pre-commit hook
• Add some other handy pre-commit fixers/linters too

---

Here's the pip installs for isodate from PyPI for March 2021, showing low numbers for EOL versions:

category	percent	downloads
3.7	51.39%	16,518,933
3.6	25.40%	8,165,006
3.8	10.28%	3,305,128
3.5	4.76%	1,529,899
2.7	3.16%	1,016,819
null	3.06%	982,390
3.9	1.92%	617,791
3.4	0.03%	10,536
3.10	0.00%	540
3.3	0.00%	15
2.6	0.00%	13
Total		32,147,070

Date range: 2021-03-01 - 2021-03-31

Source: pip install -U pypistats && pypistats python_minor isodate --last-month

[gweis]

I think most of it is included in #68 as well ?

[hugovk]

About half was in #68, I've now updated this. Thanks!

[hugovk]

Or rather, I'll update this tomorrow :)

[gweis]

from a quick glance it's only some code modernisation and formatting ... and some packaging (setup.cfg)
I am planning to move this project to poetry (pyproject.toml) and use black in the pre-commit-hook for consistent code formatting.

that should then cover everything I think.

[codecov-commenter]

Codecov Report

Merging #66 (68a4bbe) into master (d0eb6b9) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master      #66   +/-   ##
=======================================
  Coverage   94.36%   94.36%           
=======================================
  Files          10       10           
  Lines         497      497           
=======================================
  Hits          469      469           
  Misses         28       28           

Flag	Coverage Δ
GHA_Ubuntu	94.36% <100.00%> (ø)
GHA_Windows	94.36% <100.00%> (ø)
GHA_macOS	94.36% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/isodate/duration.py	93.57% <100.00%> (ø)

---

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[hugovk]

Sounds good!

This adds workflow_dispatch to GHA which adds a button to be able to trigger builds, fixes the CI to build pypy-3.8 because pypy3 is deprecated and will be removed, simplify the cache config, adds some extra things to pre-commit, deletes redundant setup.cfg because universal wheels are only for Python 2 and 3, add python_requires to help pip install the right library version for the user's Python.

[eggplants]

Any updates?