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

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/checkout	action	major	v4 → v6
actions/checkout	action	major	v4.2.2 → v6.0.2

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Release Notes

actions/checkout (actions/checkout)

v6

Compare Source

v5

Compare Source

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Configuration

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[codspeed-hq]

Merging this PR will improve performance by 14.79%

⚡ 2 improved benchmarks
✅ 10 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	original case	6.7 µs	6.1 µs	+10.81%
⚡	medium list, few solutions	1.8 ms	1.6 ms	+14.79%

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_{Comparing renovate/actions-checkout-6.x (6e83c05) with main (f471c61)}