Update ewjoachim/python-coverage-comment-action-base Docker tag to v7

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
ewjoachim/python-coverage-comment-action-base	final	major	v6 -> v7

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Configuration

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[github-actions]

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[ewjoachim]

If we do it, #468 will be the one doing it.