<!--Provide a brief description of the bug.--> SimilarityEncoder does not raise parameter Value Error at initialisation. So the user realise there is a problem only after trying to fit the encoder. <!--Please fill in the following information, to the best of your ability.--> dirty_cat version: Expected behavior: ```python SimilarityEncoder(handle_unknown='blabla') ___________________________________________________________________________________ ValueError: Got handle_unknown='blabla', but expected any of {'error', 'ignore'}. ``` Observed behavior: ```python SimilarityEncoder(handle_unknown='blabla') _______________________________________________ # No errors ```