Gate the test matrix and retry setup-uv's flaky manifest fetch #3429

Job	Run time
checks / docs	38s
checks / readme-snippets	12s
checks / pre-commit	1m 4s
checks / test (3.10, locked, windows-latest)	2m 3s
checks / test (3.11, locked, windows-latest)	1m 46s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 11s
checks / test (3.10, locked, ubuntu-latest)	1m 13s
checks / test (3.12, locked, ubuntu-latest)	1m 32s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 1s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 11s
checks / test (3.10, lowest-direct, windows-latest)	1m 53s
checks / test (3.13, locked, windows-latest)	1m 37s
checks / test (3.13, locked, ubuntu-latest)	1m 5s
checks / test (3.12, locked, windows-latest)	1m 52s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 1s
checks / test (3.11, locked, ubuntu-latest)	1m 7s
checks / test (3.13, lowest-direct, windows-latest)	1m 51s
checks / test (3.12, lowest-direct, windows-latest)	1m 30s
checks / test (3.14, lowest-direct, windows-latest)	1m 40s
checks / test (3.14, lowest-direct, ubuntu-latest)	59s
checks / test (3.11, lowest-direct, windows-latest)	1m 44s
checks / test (3.14, locked, ubuntu-latest)	2m 11s
checks / test (3.14, locked, windows-latest)	2m 52s
all-green	3s
	33m 16s

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