BUG: fix mtime of sdist archive members #533

Job	Run time
test (ubuntu, 3.7)	2m 30s
test (ubuntu, 3.11)	3m 3s
test (macos, 3.7)	5m 24s
test (macos, 3.11)	4m 4s
test (windows, 3.7)	5m 30s
test (windows, 3.11)	7m 30s
test (ubuntu, pypy-3.9)	6m 51s
test (ubuntu, 3.8)	2m 14s
test (ubuntu, 3.9)	2m 58s
test (ubuntu, 3.10)	2m 53s
test (ubuntu, 3.12-dev)	4m 39s
test (ubuntu, 3.11, ~=0.63.3)	2m 27s
test (ubuntu, 3.11, ~=0.64.0)	2m 46s
test (ubuntu, 3.11, ~=1.0.0)	2m 14s
test (ubuntu, 3.11, ~=1.1.0)	2m 9s
test (ubuntu, 3.11, @git+https://github.com/mesonbuild/meson.git)	3m 13s
mypy	9s
msvc (3.11)	7m 57s
homebrew (3.8)	7m 55s
homebrew (3.11)	8m 58s
pyston (3.8)	2m 12s
cygwin (3.9)	13m 49s
	1h 41m 25s

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