refine table markdown output #1478

Job	Run time
build (ubuntu-latest, 3.9, true, false)	2m 23s
build (ubuntu-latest, 3.9, false, true)	4m 6s
build (ubuntu-latest, 3.11, true, false)	2m 30s
build (ubuntu-latest, 3.11, false, true)	3m 54s
build (ubuntu-latest, 3.13, true, false)	2m 38s
build (ubuntu-latest, 3.13, false, true)	4m 29s
build (ubuntu-20.04, 3.8)	2m 24s
build (macos-13, 3.8)	2m 40s
build (macos-latest, 3.10)	2m 10s
build (windows-latest, 3.10)	2m 58s
build (ubuntu-latest, 3.12)	2m 46s
	32m 58s

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