Fix favicon for Chrome and Opera

[hugovk]

• Target the master branch for bug fixes, documentation updates and trivial changes.
• Target the features branch for new features, improvements, and removals/deprecations.
• Include documentation when adding new features.
• Include new tests or update existing tests when applicable.

Unless your change is trivial or a small documentation fix (e.g., a typo or reword of a small section) please:

• [n/a?] Create a new changelog file in the changelog folder, with a name like <ISSUE NUMBER>.<TYPE>.rst. See changelog/README.rst for details.

  Write sentences in the past or present tense, examples:

  • Improved verbose diff output with sequences.
  • Terminal summary statistics now use multiple colors.

  Also make sure to end the sentence with a ..

• Add yourself to AUTHORS in alphabetical order.

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Old favicon

Right now, the favicon shows as a blank white box in Chrome and Opera. It's fine in Firefox.

The old doc/en/img/pytest1favi.ico from 2014 has two frames, one Pytest logo with a transparent background and one plain white box.

Different browsers pick a different frame.

macOS Chrome 79

macOS Opera 65

macOS Firefox 72

Android Chrome 79

New favicon

Converted to PNG frames using ImageMagick, updated config to use the logo frame:

convert doc/en/img/pytest1favi.ico favicon.png
cp favicon-0.png doc/en/img/favicon.png
sphinx-build -W --keep-going -b html doc/en doc/en/_build -t changelog_towncrier_draft
open doc/en/_build/index.html

The conf.py comments say "This file should be a Windows icon file (.ico) being 16x16 or 32x32 pixels large", but PNG works fine in 2020.

macOS Chrome 79

macOS Opera 65

macOS Firefox 72

TODO

• Remove old file?

[nicoddemus]

Thanks @hugovk! Took the liberty of removing the old one myself. 👍