Add scalafmt plugin to scala-sttp client generator #45

Job	Run time
Build sbt/Scala (samples/client/petstore/scala-http4s)	1m 2s
Build sbt/Scala (samples/client/petstore/scala-sttp)	1m 0s
Build sbt/Scala (samples/client/petstore/scala-sttp-circe)	1m 11s
Build sbt/Scala (samples/client/petstore/scalaz)	1m 7s
Build sbt/Scala (samples/client/petstore/scala-akka)	1m 15s
Build sbt/Scala (samples/client/petstore/scala-pekko)	1m 7s
Build sbt/Scala (samples/client/petstore/scala-sttp4)	1m 2s
Build sbt/Scala (samples/client/petstore/scala-sttp4-jsoniter)	1m 1s
	8m 45s

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