tests: Добавление теста с полем (multipart) с несколькими значениями #96

Job	Run time
test (dev) / build (macos-latest, dev)	1m 52s
test (stable) / build (windows-latest, stable)	1m 11s
test (stable) / build (macos-latest, stable)	2m 40s
test (stable) / build (ubuntu-latest, stable)	2m 48s
test (dev) / build (windows-latest, dev)	1m 13s
test (dev) / build (ubuntu-latest, dev)	2m 12s
	11m 56s

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