revert: Fix Pylance warning

mleko/dataset/transform/label_encoder_transformer.py

@@ -145,7 +145,7 @@ def _fit(
         logger.info(f"Fitting label encoder transformer ({len(self._features)}): {self._features}.")
         for feature in self._features:
             self._ensure_valid_feature_type(feature, data_schema, dataframe)
-            labels = get_column(dataframe, feature).unique(dropna=True)
+            labels: list[str] = get_column(dataframe, feature).unique(dropna=True)  # type: ignore
             if not self._fit_using_label_dict(feature, labels):
                 logger.info(f"Assigning mappings for feature {feature!r}: {labels}.")
                 self._transformer[feature] = {label: i for i, label in enumerate(labels)}