Add automated Rust toolchain upgrade workflow #747

Job	Run time
Difftest (macOS-latest)	11m 44s
Difftest (ubuntu-24.04)	11m 42s
Difftest (windows-2022)	22m 10s
Android (ubuntu-24.04, aarch64-linux-android)	8m 3s
Compiletest (macOS-latest)	6m 59s
Compiletest (windows-2022)	16m 16s
Compiletest (ubuntu-24.04)	8m 46s
Test (ubuntu-24.04)	8m 16s
Test (windows-2022)	14m 51s
Test (macOS-latest)	7m 43s
cargo-deny	1m 19s
Lint	5m 40s
test_success	2s
	2h 3m 31s

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