chore(deps): update dependency pytest-cov to v6

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
pytest-cov (changelog)	^5.0 -> ^6.0.0

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Release Notes

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

v6.0.0

Compare Source

• 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.

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Configuration

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♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

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[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: poetry.lock

Updating dependencies
Resolving dependencies...

Creating virtualenv powercalc-A-h5NqUf-py3.12 in /home/ubuntu/.cache/pypoetry/virtualenvs

Because powercalc depends on pytest-homeassistant-custom-component (0.13.175) which depends on pytest-cov (5.0.0), pytest-cov is required.
So, because powercalc depends on pytest-cov (^6.0.0), version solving failed.