Tests

Added `files_upload_external` #1357

Job	Run time
test (ruby=2.7)	32s
test (ruby=2.7, concurrency=async-websocket)	37s
test (ruby=3.0)	19s
test (ruby=3.1)	20s
test (ruby=3.2)	20s
test (ruby=3.3)	23s
test (ruby=ruby-head)	20s
test (ruby=jruby-head)	1m 53s
coveralls	2s
	4m 46s

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