Bump actions/cache from 4.1.2 to 4.2.1 #999

Job	Run time
Build and test cmake:gcc9	30s
Build and test cmake:clang15	43s
Build and test cmake:clang:asan	42s
Build and test cmake:clang:tsan	52s
Build and test cmake:clang:ubsan	46s
Build and test cmake:qemu-arm-neon-gcc	1m 45s
Build and test cmake-osx:clang	29s
Build and test cmake-osx:gcc	23s
Build and test cmake-win64:msvc-rel	52s
Build and test cmake-win64:msvc-dbg	1m 2s
Build and test fuzz:clang	42s
Build and test python3.10:clang	1m 46s
Build and test python3.10-win	1m 21s
Build and test maven	24s
Build and test bazel:root	35s
Build and test bazel:go	1m 16s
Build and test bazel:java	2m 9s
Build and test bazel:research	25s
Build and test bazel-osx:root	1m 3s
Build and test bazel-osx:go	1m 3s
Build and test bazel-osx:java	3m 3s
Build and test bazel-osx:research	49s
Build and test bazel-win:root	1m 43s
Build and test bazel-win:java	2m 14s
Build and test bazel-win:research	1m 44s
	28m 21s

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