rustup: update to `nightly-2025-06-23` (~1.89). #653

Job	Run time
Test (windows-2022)	14m 48s
Test (ubuntu-24.04)	8m 9s
Difftest (macOS-latest)	14m 52s
Difftest (ubuntu-24.04)	9m 50s
Difftest (windows-2022)	17m 13s
Android (ubuntu-24.04, aarch64-linux-android)	8m 19s
Compiletest (ubuntu-24.04)	8m 21s
Compiletest (windows-2022)	16m 20s
Compiletest (macOS-latest)	7m 40s
cargo-deny	1m 11s
Test (macOS-latest)	6m 48s
Lint	6m 13s
test_success	3s
	1h 59m 47s

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