chore(deps): update actions/setup-python action to v6.3.0 (#1456) #3384

Job	Run time
Integration Tests (pdm.minimal.lock)	30s
test_min_deps (ubuntu-latest)	44s
test_min_deps (macos-latest)	30s
test_min_deps (windows-latest)	1m 34s
test (3.11, windows-latest)	1m 21s
test (3.11, ubuntu-latest)	51s
Integration Tests (pdm.lock)	30s
test (3.14, macos-latest)	42s
test (3.12, ubuntu-latest)	1m 0s
test (3.12, windows-latest)	1m 20s
test (3.13, macos-latest)	44s
test (3.12, macos-latest)	51s
test (3.14, ubuntu-latest)	44s
test (3.13, ubuntu-latest)	57s
test (3.13, windows-latest)	1m 24s
test (3.11, macos-latest)	40s
test (3.14, windows-latest)	1m 19s
Combine & check coverage	13s
	15m 54s

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