Tests

Add group ID formatting support for message mentions #1437

Job	Run time
test (ruby=2.7)	31s
test (ruby=2.7, concurrency=async-websocket)	37s
test (ruby=3.0)	19s
test (ruby=3.1)	19s
test (ruby=3.2)	24s
test (ruby=3.3)	21s
test (ruby=3.4)	19s
test (ruby=ruby-head)	19s
test (ruby=jruby-head)	1m 59s
coveralls	3s
	5m 11s

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