Update allowed docs versions and add backfill workflow #6271

Job	Run time
build_linux (3.14)	5m 42s
build_linux (3.13)	5m 45s
build_linux (3.11)	5m 54s
build_linux (3.10)	6m 14s
build_windows (3.13)	9m 16s
build_linux (3.12)	6m 17s
build_windows (3.14)	8m 52s
build_windows (3.12)	10m 35s
build_windows (3.11)	8m 49s
build_windows (3.10)	9m 29s
test_examples_linux (3.11, false, ubuntu-latest)	5m 11s
test_linux (3.14, false, ubuntu-latest)	2m 47s
test_linux (3.13, false, ubuntu-latest)	2m 50s
test_linux (3.10, false, ubuntu-latest)	3m 12s
test_linux (3.11, false, ubuntu-latest)	2m 33s
test_linux (3.12, false, ubuntu-latest)	2m 45s
upload_linux	-1s
test_windows (3.10, false, windows-latest)	4m 24s
test_windows (3.14, false, windows-latest)	4m 4s
test_windows (3.13, false, windows-latest)	3m 27s
test_windows (3.11, false, windows-latest)	3m 23s
test_windows (3.12, false, windows-latest)	3m 6s
upload_windows	0s
Clean up anaconda packages	0s
	1h 54m 34s

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