Update certifi to 2020.12.5

[pyup-bot]

This PR updates certifi from 2019.6.16 to 2020.12.5.

The bot wasn't able to find a changelog for this release. Got an idea?

Links

• PyPI: https://pypi.org/project/certifi
• Docs: https://certifiio.readthedocs.io/en/latest/

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@9648034). Click here to learn what that means.
The diff coverage is 100.00%.

@@ Coverage Diff @@## master #410 +/- ##
==========================================
Coverage ? 100.00% ==========================================
Files ? 12 Lines ? 116 Branches ? 0 ==========================================
Hits ? 116 Misses ? 0 Partials ? 0 

Impacted Files	Coverage Δ
libpythonpro/github_api.py	100.00% <ø> (ø)
...ythonpro/tests/test_spam/test_enviador_de_email.py	100.00% <100.00%> (ø)
...ests/test_spam/test_envio_para_base_de_usuarios.py	100.00% <100.00%> (ø)
libpythonpro/tests/test_spam/test_github_api.py	100.00% <100.00%> (ø)

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[pyup-bot]

Closing this in favor of #535