Fix detection of object properties in read operation

Author: nikitinas

src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/toDataFrame.kt

@@ -41,7 +41,9 @@ public inline fun <reified T> DataColumn<T>.read(): AnyCol = when (kind()) {
         isPrimitive() -> this
         typeClass == File::class -> cast<File?>().mapNotNullValues { DataFrame.read(it) }
         typeClass == URL::class -> cast<URL?>().mapNotNullValues { DataFrame.read(it) }
-        else -> values().toDataFrame().asColumnGroup(name()).asDataColumn()
+        else -> values().createDataFrameImpl(typeClass) {
+            (this as CreateDataFrameDsl<T>).properties(depth = 1)
+        }.asColumnGroup(name()).asDataColumn()
     }
 }