Tests

Update API from slack-api-ref@c408935 (2025-06-04) #1660

Job	Run time
test (ruby=2.7, concurrency=async-websocket)	44s
test (ruby=3.1)	41s
test (ruby=2.7)	41s
test (ruby=3.0)	37s
test (ruby=3.2)	25s
test (ruby=ruby-head)	30s
test (ruby=jruby-head)	2m 58s
test (ruby=3.4)	31s
test (ruby=3.3)	35s
coveralls	3s
	7m 45s

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