Update GitHub Actions to v7 (#271) #804

Job	Run time
ci (highest, ubuntu-24.04, 3.14, nocov)	10m 54s
ci (highest, windows-2025, 3.14, nocov)	1m 8s
ci (highest, macos-15, 3.10, nocov)	7m 48s
ci (ubuntu-24.04, 3.11, nocov, lowest-direct)	8m 12s
ci (highest, macos-15, 3.14, nocov)	8m 21s
ci (lowest-direct, ubuntu-24.04, 3.14, nocov)	10m 27s
ci (highest, windows-2025, 3.10, nocov)	1m 8s
ci (ubuntu-24.04, 3.12, nocov, lowest-direct)	10m 39s
ci (lowest-direct, windows-2025, 3.14, nocov)	1m 8s
ci (highest, ubuntu-24.04, 3.10, nocov)	10m 55s
ci (lowest-direct, ubuntu-24.04, 3.10, nocov)	9m 54s
ci (ubuntu-24.04, 3.14, cov, lowest-direct)	10m 32s
ci (lowest-direct, macos-15, 3.14, nocov)	7m 22s
ci (ubuntu-24.04, 3.13, nocov, lowest-direct)	10m 54s
ci (lowest-direct, macos-15, 3.10, nocov)	7m 19s
ci (lowest-direct, windows-2025, 3.10, nocov)	1m 10s
publish	1m 21s
	1h 59m 12s

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