Add Codecov to gensim repo

[menshikh-iv]

Fix #2002

CC @mpenkov, I need you to follow instruction from https://docs.codecov.com/docs#basic-usage to have an upload token available in github actions (or just integrations with github repo)

What's need to add after token will be available:

• Add --cov-report=xml to pytest
• After tox test run, upload coverage report (probably only from single job, like py38-linux), see https://github.com/codecov/codecov-action#example-workflowyml-with-codecov-action as reference

[mpenkov]

Waiting for @piskvorky to approve codecov access to the gensim repo (he's the repo owner). I think codecov has sent the request by email.

[piskvorky]

It has. But the app is asking for permissions to access private data, which I cannot do:

[menshikh-iv]

@piskvorky can you please try to add codecov as app form here https://github.com/marketplace/codecov/plan/MDIyOk1hcmtldHBsYWNlTGlzdGluZ1BsYW4xNg==

In that case, you should have a way to select a repo

[piskvorky]

Thanks, done: I "installed" that app into 4 public repos: Gensim, smart-open, sqlitedict and bounter.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (develop@5bec277). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             develop    #3252   +/-   ##
==========================================
  Coverage           ?   78.88%           
==========================================
  Files              ?       68           
  Lines              ?    11772           
  Branches           ?        0           
==========================================
  Hits               ?     9286           
  Misses             ?     2486           
  Partials           ?        0           

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[mpenkov]

Good work @menshikh-iv . Thank you!!