Fix test and add deprecation level

Author: koperagen

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/common.kt

@@ -48,6 +48,7 @@ public fun catchHttpResponse(url: URL, body: (InputStream) -> AnyFrame): AnyFram
 @Deprecated(
     LISTS_TO_DATAFRAME_MIGRATION,
     ReplaceWith("this.toDataFrame(header = null, containsColumns)", "org.jetbrains.kotlinx.dataframe.api.toDataFrame"),
+    level = DeprecationLevel.WARNING,
 )
 public fun <T> List<List<T>>.toDataFrame(containsColumns: Boolean = false): AnyFrame =
     toDataFrame(header = null, containsColumns)

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/api/toDataFrame.kt

@@ -713,7 +713,7 @@ class CreateDataFrameTests {
             }
         }
 
-        val df = lines.chunked(3).toDataFrame()
+        val df = lines.chunked(3).toDataFrame(header = null)
 
         df.columnNames() shouldBe listOf("stamp", "header", "data")
         df.columnTypes() shouldBe listOf(typeOf<String>(), typeOf<String>(), typeOf<String>())