Add latest Python versions

[ecederstrand]

Adds Python 3.8 as a supported version in package metadata and includes this version in CI tests.

To accept your contribution, please ensure that the checklist below is complete.

• Is your name/identity in the AUTHORS file?
• Does the code change (if the PR contains code) have 100% test coverage?
• Is CI passing all quality and testing checks?

[mblayman]

Codecov Report

Merging #109 into master will not change coverage by %.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #109   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           12        12           
  Lines          576       602   +26     
=========================================
+ Hits           576       602   +26     

Impacted Files	Coverage Δ
tap/line.py	100.00% <0.00%> (ø)	⬆️
tap/runner.py	100.00% <0.00%> (ø)	⬆️
tap/directive.py	100.00% <0.00%> (ø)	⬆️

---

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[mblayman]

This looks pretty good! I didn't realize Travis added Python 3.8 support so thanks for making this update.

Could you also update the README.md, docs/index.rst, and docs/releases.rst file to mention 3.8? There should be examples from other releases that you can pull from in releases.rst. For releases.rst, I do something like:

Version 3.1, To Be Released
---------------------------

when creating a new section for a release that isn't out yet.

[codecov-io]

Codecov Report

Merging #109 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #109   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          12     12           
  Lines         576    602   +26     
=====================================
+ Hits          576    602   +26

Impacted Files	Coverage Δ
tap/directive.py	100% <0%> (ø)	⬆️
tap/runner.py	100% <0%> (ø)	⬆️
tap/line.py	100% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7ab5bd7...9d2ec68. Read the comment docs.

[ecederstrand]

Sure. I've updated the files as requested.

Travis even has a nightly target, if you want to test on the bleeding edge :-)

[mblayman]

LGTM 👍