Add automated Rust toolchain upgrade workflow #744

Job	Run time
Android (ubuntu-24.04, aarch64-linux-android)	8m 6s
Test (windows-2022)	14m 9s
Test (macOS-latest)	6m 44s
Test (ubuntu-24.04)	8m 13s
Compiletest (windows-2022)	16m 3s
cargo-deny	1m 7s
Lint	5m 48s
Compiletest (macOS-latest)	11m 15s
Compiletest (ubuntu-24.04)	8m 31s
Difftest (ubuntu-24.04)	11m 44s
Difftest (windows-2022)	22m 43s
Difftest (macOS-latest)	13m 1s
test_success	4s
	2h 7m 28s

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