Add artificial delay to find_illegal_dependencies

[seddonym]

Adding a sleep doesn't seem to affect the benchmarking for some reason.

I've asked on the Codspeed discord: https://discord.com/channels/1065233827569598464/1249695480204755076/1249695480204755076

[codspeed-hq]

CodSpeed Performance Report

Merging #150 will degrade performances by 98.12%

_{Comparing codspeed-demo (eb03c2c) with master (cfb43d6)}

Summary

❌ 2 regressions

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	master	codspeed-demo	Change
❌	test_deep_layers_large_graph	5.8 s	77.3 s	-92.45%
❌	test_top_level_large_graph	1.4 s	72.9 s	-98.12%