Clippy fixes

src/preprocessing/mod.rs

@@ -1,5 +1,5 @@
 /// Transform a data matrix by replaceing all categorical variables with their one-hot vector equivalents
-pub mod categorical_encoders;
+pub mod categorical_encoder;
 mod data_traits;
 /// Encode a series (column, array) of categorical variables as one-hot vectors
 pub mod series_encoder;