chore(deps): update actions/checkout action to v6

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v5.0.1 -> v6.0.0

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Release Notes

actions/checkout (actions/checkout)

v6.0.0

Compare Source

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Configuration

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🚦 Automerge: Enabled.

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[codspeed-hq]

CodSpeed Performance Report

Merging #868 will improve performances by 3.05%

_{Comparing renovate/major-github-actions (29fab34) with main (8ef6c6d)}

Summary

⚡ 1 improvement
✅ 10 untouched
⏩ 5 skipped¹

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	resolver_real[multi-thread]	505.9 µs	490.9 µs	+3.05%

Footnotes

1. 5 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩