test

gha: use checkout v4 #283

Job	Run time
build (buster, mcode)	4m 34s
build (bullseye, mcode)	3m 56s
build (bullseye, mcode, --gplcompat)	3m 17s
build (bookworm, mcode, --gplcompat)	3m 23s
build (ubuntu20, mcode)	4m 34s
build (ubuntu22, mcode)	3m 53s
build (fedora37, mcode)	3m 40s
build (fedora38, mcode)	3m 41s
build (bullseye, llvm-11)	10m 34s
build (ubuntu20, llvm-10)	11m 39s
build (ubuntu22, llvm-11)	10m 41s
build (fedora37, llvm)	9m 44s
build (fedora38, llvm)	10m 7s
build (bullseye, gcc-9.4.0)	17m 4s
build (fedora37, gcc-10.3.0)	43s
build (fedora38, gcc-11.3.0)	48s
	1h 42m 18s

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