Update Rust toolchains to nightly-2026-04-27 #8682

Performance Regression: -20.54%

⚡ 1 improved benchmark
❌ 5 regressed benchmarks
✅ 74 untouched benchmarks

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

	Benchmark	`BASE`	`HEAD`	Efficiency
👁	`pattern_match_constant`	180 ns	150.8 ns	+19.34%
❌	`bit_matrix/dense/transitive_closure[200]`	754.4 µs	907.1 µs	-16.83%
❌	`bit_matrix/dense/transitive_closure[16]`	4.8 µs	5.9 µs	-19.31%
❌	`bit_matrix/dense/transitive_closure[64]`	56.4 µs	71 µs	-20.54%
❌	`bit_matrix/sparse/union_rows[200]`	12.1 µs	13.8 µs	-12.55%
❌	`bit_matrix/sparse/union_rows[64]`	4 µs	4.5 µs	-10.93%

_{Comparing deps/rs/rust-toolchains (2f0d2b8) with main (891f36f)}