Fix test port import (mongodb#1435)

Author: rozza

bson-kotlin/src/test/kotlin/org/bson/codecs/kotlin/samples/DataClasses.kt

@@ -15,7 +15,6 @@
  */
 package org.bson.codecs.kotlin.samples
 
-import kotlinx.serialization.Serializable
 import kotlin.time.Duration
 import org.bson.BsonDocument
 import org.bson.BsonMaxKey