Update Rust crate tempfile to v3.12.0 #256

Job	Run time
cargo clippy -- -D warnings (ubuntu-latest)	11s
cargo check (ubuntu-latest)	8s
cargo clippy -- -D warnings (macOS-latest)	12s
cargo check (macOS-latest)	10s
cargo clippy -- -D warnings (windows-latest)	1m 37s
cargo check (windows-latest)	1m 33s
Code Coverage (ubuntu-latest, unix)	2m 8s
Code Coverage (macos-latest, macos)	2m 35s
cargo fmt --all -- --check	5s
Code Coverage (windows-latest, windows)	5m 54s
GNU test suite	1m 41s
cargo test (ubuntu-latest)	44s
cargo test (macOS-latest)	2m 54s
cargo test (windows-latest)	3m 37s
	23m 29s

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