chore(deps): update actions/cache action to v6 (#1454) #3374

Job	Run time
Integration Tests (pdm.lock)	40s
test_min_deps (macos-latest)	39s
test_min_deps (ubuntu-latest)	39s
test_min_deps (windows-latest)	1m 22s
test (3.14, macos-latest)	50s
test (3.13, windows-latest)	1m 24s
Integration Tests (pdm.minimal.lock)	34s
test (3.12, macos-latest)	44s
test (3.11, macos-latest)	56s
test (3.13, macos-latest)	52s
test (3.13, ubuntu-latest)	1m 4s
test (3.11, ubuntu-latest)	56s
test (3.12, ubuntu-latest)	1m 10s
test (3.14, ubuntu-latest)	1m 0s
test (3.14, windows-latest)	1m 18s
test (3.11, windows-latest)	1m 18s
test (3.12, windows-latest)	1m 23s
Combine & check coverage	12s
	17m 1s

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