rename(Pair<String, String>) assigns new names in the wrong order

Given:
```
val df = listOf(
  Triple(1, 10, 0.1),
  Triple(2, 20, 0.2)
).toDataFrame()
  .rename("first" to "id", "second" to "df_count", "third" to "df_ratio")
```
This
```
df.rename(
  "df_ratio" to "ratio_df",
  "df_count" to "count_df"
)
```
Should be `id, count_df, ratio_df`, but now is `id, ratio_df, count_df`, so columns are assigned a new name in the order they occur in the dataframe