Update actions/checkout action to v6

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v5 → v6
actions/checkout	action	major	v4 → v6

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Release Notes

actions/checkout (actions/checkout)

v6.0.2

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• Fix tag handling: preserve annotations and explicit fetch-tags by @​ericsciple in #​2356

v6.0.1

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v6.0.0

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v6

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v5.0.1

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What's Changed

• Port v6 cleanup to v5 by @​ericsciple in #​2301

Full Changelog: actions/checkout@v5...v5.0.1

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