workflows/docs: allow reading GitHub Pages. #27967

Job	Run time
syntax	57s
cask audit	2m 46s
formula audit	6m 24s
tap syntax	4m 28s
docker	4m 29s
update-test (Ubuntu 22.04)	1m 13s
update-test (macOS 13)	1m 6s
vendored gems	55s
test default formula (Ubuntu 22.04)	4m 27s
test default formula (Ubuntu 20.04)	5m 46s
tests (online)	9m 27s
test default formula (macOS 13 x86_64)	2m 32s
tests (generic OS)	6m 7s
test default formula (macOS 14 arm64)	1m 17s
tests (Ubuntu 22.04)	6m 11s
tests (Ubuntu 20.04)	6m 36s
tests (macOS 13 x86_64)	6m 35s
tests (macOS 14 arm64)	4m 37s
	1h 15m 53s

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