[v1.x] ci: pick the docs toolchain per worktree in build-docs.sh #4321

Job	Run time
checks / pre-commit	28s
checks / test (3.11, highest, windows-latest)	2m 18s
checks / test (3.10, lowest-direct, ubuntu-latest)	48s
checks / test (3.12, highest, ubuntu-latest)	52s
checks / test (3.10, lowest-direct, windows-latest)	2m 14s
checks / test (3.12, highest, windows-latest)	2m 54s
checks / test (3.12, lowest-direct, ubuntu-latest)	47s
checks / test (3.11, lowest-direct, ubuntu-latest)	45s
checks / test (3.12, lowest-direct, windows-latest)	3m 22s
checks / test (3.14, highest, ubuntu-latest)	1m 9s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 7s
checks / test (3.13, highest, ubuntu-latest)	44s
checks / test (3.14, lowest-direct, windows-latest)	2m 15s
checks / test (3.13, highest, windows-latest)	2m 36s
checks / test (3.14, highest, windows-latest)	2m 18s
checks / test (3.13, lowest-direct, windows-latest)	2m 22s
checks / test (3.13, lowest-direct, ubuntu-latest)	52s
checks / doc-snippets	11s
checks / test (3.10, highest, ubuntu-latest)	47s
checks / test (3.11, highest, ubuntu-latest)	46s
checks / test (3.10, highest, windows-latest)	2m 16s
checks / test (3.11, lowest-direct, windows-latest)	2m 37s
all-green	4s
	34m 32s

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