build

Bump version: 3.9.28 → 3.9.29-alpha.0 #1809

Job	Run time
check	43s
docs	1m 9s
py39 (windows)	12m 4s
py39 (ubuntu)	10m 9s
py310 (windows)	12m 14s
py311 (macos)	6m 51s
py310 (ubuntu)	10m 20s
py38 (ubuntu)	10m 18s
py311 (windows)	13m 9s
py311 (ubuntu)	10m 0s
Deploy docs to GitHub Pages	1m 9s
Upload coverage to Coveralls	9m 59s
	1h 38m 5s

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