Ruby: Add ability to install gem from a branch #1069

Job	Run time
Build x86_64-linux-musl gem	3m 14s
Build arm-linux-musl gem	3m 29s
Build arm64-darwin gem	4m 0s
Build x86-linux-musl gem	3m 24s
Build aarch64-linux-musl gem	3m 23s
Build x86_64-darwin gem	4m 26s
Build aarch64-linux-gnu gem	3m 46s
Build x86_64-linux-gnu gem	3m 28s
Build arm-linux-gnu gem	3m 34s
Build x86-linux-gnu gem	3m 10s
Build default gem	1m 58s
Push gems with trusted publishing	0s
	37m 52s

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