deps: bump nybbles to 0.4

[shekhirin]

Bump nybbles to version 0.4.

This PR doesn't contain any breaking changes to the user-facing API, such as method signatures.

[codspeed-hq]

CodSpeed Performance Report

Merging #104 will degrade performances by 17.15%

_{Comparing alexey/nybbles-uint (520a961) with main (816689b)}

Summary

❌ 3 regressions
✅ 1 untouched benchmarks

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

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	trie[16]	418.1 ns	495.6 ns	-15.64%
❌	trie[32]	438.1 ns	501.7 ns	-12.68%
❌	trie[8]	408.1 ns	492.5 ns	-17.15%