ci: rework GitHub caching strategy #8665

Job	Run time
fmt	16s
emscripten	0s
check-feature-powerset	0s
careful	0s
python${{ matrix.python-version }}-${{ matrix.platform.python-architecture }} ${{ matrix.platform.os }} rust-${{ matrix.rust }}	0s
check-msrv	12m 34s
coverage-windows	5s
semver-checks	2m 34s
docsrs	0s
coverage-macos	5s
test-debug	9m 30s
coverage-ubuntu	11m 49s
clippy/x86_64-apple-darwin/stable	20m 38s
test-version-limits	0s
clippy/x86_64-unknown-linux-gnu/stable	10m 30s
valgrind	0s
clippy/powerpc64le-unknown-linux-gnu/stable	9m 34s
clippy/s390x-unknown-linux-gnu/stable	9m 47s
clippy/wasm32-wasi/stable	9m 3s
clippy/x86_64-pc-windows-msvc/stable	15m 18s
clippy/i686-pc-windows-msvc/stable	14m 31s
clippy/x86_64-unknown-linux-gnu/beta	10m 5s
python3.12-x64 windows-latest rust-stable / build	13m 13s
python3.12-x86 windows-latest rust-stable / build	12m 9s
python3.12-x64 ubuntu-latest rust-stable / build	8m 42s
python3.12-x64 macos-latest rust-stable / build	9m 7s
python3.12-x64 ubuntu-latest rust-nightly / build	1m 24s
conclusion	1s
	3h 0m 55s

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