Tests

Added `files_upload_external` #1359

Job	Run time
test (ruby=2.7)	32s
test (ruby=2.7, concurrency=async-websocket)	34s
test (ruby=3.0)	18s
test (ruby=3.1)	19s
test (ruby=3.2)	20s
test (ruby=3.3)	20s
test (ruby=ruby-head)	30s
test (ruby=jruby-head)	1m 49s
coveralls	2s
	4m 44s

Provide feedback