Delay CI cache restore until the toolchain has been installed. #5

Job	Run time
cargo clippy (wasm32)	16s
cargo test (windows-latest)	33s
cargo check (msrv) (wasm32)	15s
cargo test (macos-latest)	21s
cargo check (msrv) (windows-latest)	36s
cargo test (ubuntu-latest)	12s
cargo clippy (windows-latest)	43s
cargo clippy (macos-latest)	25s
cargo check (msrv) (macos-latest)	24s
cargo doc	16s
cargo clippy (ubuntu-latest)	21s
cargo check (msrv) (ubuntu-latest)	15s
formatting	21s
cargo test (wasm32)	12s
typos	4s
	5m 14s

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