Update dependencies

[qutebrowser-bot]

Changed files

• tests
• tox
• vulture

Version updates

Requirement	old	new
cheroot	8.4.1	8.4.2
hypothesis	5.23.2	5.23.3
iniconfig	--	1.0.0
pytest	5.4.3	6.0.0
toml	--	0.10.1
tox	3.18.0	3.18.1
vulture	1.5	1.6
wcwidth	0.2.5	--

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[The-Compiler]

todo for pytest

• Add iniconfig changelog
• Work around pytest 6: pylint still shows not-callable error for builtin pytest marks even after #7473 and #7476 pytest-dev/pytest#7558
• Replace --strict with --strict-markers --strict-config
• Remove pytrace=False workaround
• Set required_plugins