BLD: add missing dependency on `packaging` #2395

Job	Run time
mypy	12s
cygwin (3.9)	6m 13s
homebrew (3.8)	2m 19s
msvc (3.11)	3m 16s
homebrew (3.11)	1m 57s
pyston (3.8)	1m 21s
test (ubuntu, 3.7)	1m 42s
test (ubuntu, 3.12)	2m 17s
test (macos, 3.7)	3m 35s
test (macos, 3.12)	5m 30s
test (windows, 3.7)	3m 20s
test (windows, 3.12)	4m 50s
test (ubuntu, pypy-3.9)	5m 22s
test (ubuntu, pypy-3.10)	5m 11s
test (ubuntu, 3.8)	1m 43s
test (ubuntu, 3.9)	1m 43s
test (ubuntu, 3.10)	2m 10s
test (ubuntu, 3.11, ~=0.63.3)	1m 48s
test (ubuntu, 3.11, ~=0.64.0)	2m 47s
test (ubuntu, 3.11, ~=1.0.0)	1m 47s
test (ubuntu, 3.11, ~=1.1.0)	1m 53s
test (ubuntu, 3.12, ~=1.2.3)	1m 47s
test (ubuntu, 3.12, ~=1.3)	2m 1s
test (ubuntu, 3.12, @git+https://github.com/mesonbuild/meson.git)	1m 58s
test (windows, 3.12, @git+https://github.com/mesonbuild/meson.git)	4m 42s
	1h 11m 24s

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