build_docs: add ruby-dev package #33

Job	Run time
windows (windows-2019)	2h 8m 13s
macos (macos-11, auto_index contract)	15m 29s
windows (windows-2022)	2h 5m 5s
linux (ubuntu-latest, ubuntu:22.04, python2, auto_index)	1h 13m 12s
macos (macos-11, contract, --boostrelease)	15m 27s
windows (windows-2019, -boostrelease)	1h 34m 44s
linux (ubuntu-latest, ubuntu:20.04, python, auto_index)	1h 15m 32s
windows (windows-2022, -boostrelease)	1h 37m 47s
macos (macos-12, auto_index contract)	4m 45s
linux (ubuntu-latest, ubuntu:22.04, python2, --boostrelease)	1h 0m 23s
linux (ubuntu-latest, ubuntu:20.04, python, --boostrelease)	59m 2s
macos (macos-12, contract, --boostrelease)	4m 28s
	12h 34m 7s

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