ci: bump actions/checkout to v4

[fargito]

No description provided.

[codspeed-hq]

CodSpeed Performance Report

Merging #47 will degrade performances by 41.01%

_{Comparing chore/actions-checkout-v4 (f7999ae) with master (d1c3db8)}

Summary

⚡ 4 improvements
❌ 4 (👁 4) regressions
✅ 92 untouched benchmarks

Benchmarks breakdown

	Benchmark	master	chore/actions-checkout-v4	Change
👁	test_hostname_resolution[google.com]	70.5 µs	114.6 µs	-38.47%
👁	test_multiprocessing_map[100000]	96 ms	102.1 ms	-5.95%
⚡	test_multiprocessing_map[10000]	16.3 ms	12 ms	+35.47%
⚡	test_multiprocessing_map[1000]	7.1 ms	6 ms	+18.99%
⚡	test_multiprocessing_map[100]	4.9 ms	3.6 ms	+33.75%
👁	test_multiprocessing_map[10]	2.8 ms	3.1 ms	-10.42%
⚡	test_open_close_fd[10]	37.2 µs	36.1 µs	+2.8%
👁	test_tcp_connection[google.com-443]	64.2 µs	108.9 µs	-41.01%

[art049]

We'll need to ignore those new syscall heavy benches