Update dependency pytest-cov to v6

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
pytest-cov (changelog)	^4.1.0 -> ^6.0.0

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Release Notes

pytest-dev/pytest-cov (pytest-cov)

v6.0.0

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• Updated various documentation inaccuracies, especially on subprocess handling.
• Changed fail under checks to use the precision set in the coverage configuration.
  Now it will perform the check just like coverage report would.
• Added a --cov-precision cli option that can override the value set in your coverage configuration.
• Dropped support for now EOL Python 3.8.

v5.0.0

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• Removed support for xdist rsync (now deprecated).
  Contributed by Matthias Reichenbach in #&#8203;623 <https://github.com/pytest-dev/pytest-cov/pull/623>_.
• Switched docs theme to Furo.
• Various legacy Python cleanup and CI improvements.
  Contributed by Christian Clauss and Hugo van Kemenade in
  #&#8203;630 <https://github.com/pytest-dev/pytest-cov/pull/630>,
  #&#8203;631 <https://github.com/pytest-dev/pytest-cov/pull/631>,
  #&#8203;632 <https://github.com/pytest-dev/pytest-cov/pull/632>_ and
  #&#8203;633 <https://github.com/pytest-dev/pytest-cov/pull/633>_.
• Added a pyproject.toml example in the docs.
  Contributed by Dawn James in #&#8203;626 <https://github.com/pytest-dev/pytest-cov/pull/626>_.
• Modernized project's pre-commit hooks to use ruff. Initial POC contributed by
  Christian Clauss in #&#8203;584 <https://github.com/pytest-dev/pytest-cov/pull/584>_.

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