Tests

Added `files_upload_external` #1360

Job	Run time
test (ruby=2.7)	32s
test (ruby=2.7, concurrency=async-websocket)	31s
test (ruby=3.0)	18s
test (ruby=3.1)	20s
test (ruby=3.2)	27s
test (ruby=3.3)	21s
test (ruby=ruby-head)	20s
test (ruby=jruby-head)	1m 56s
coveralls	5s
	4m 50s

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