Bump andymckay/cancel-action from 0.3 to 0.4 #80

Job	Run time
(Linux) Builds (aarch64-linux-android)	1m 31s
(OS X) Builds (aarch64-apple-ios)	2m 28s
(Linux) Builds (x86_64-unknown-linux-musl)	1m 20s
(OS X) Builds (x86_64-apple-darwin)	2m 23s
(Windows) Builds (x86_64-pc-windows-msvc)	53s
(Linux) Builds (wasm32-unknown-unknown)	54s
Bench Compile (stable)	52s
Check (stable)	12s
Rustfmt (nightly)	15s
Check (beta)	14s
Test Suite (stable)	1m 44s
Test Suite (1.70.0)	1m 15s
Check (1.70.0)	15s
	14m 16s

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