text: Title: [BUG] feature_utils unit tests failing mypy
  Body: **Describe the bug**
  
  Regular PR fails on mypy analysis of feature_utils: https://github.com/graphistry/pygraphistry/actions/runs/9800176651/job/27061697437?pr=573
  
  
  **PyGraphistry API client environment**
   - Where run: GHA CI
   - Version: 0.33.8 (main)
  
  **Additional context**
  
  ```
  + mypy --config-file mypy.ini graphistry
  graphistry/feature_utils.py:39: error: Cannot assign to a type  [misc]
  graphistry/feature_utils.py:39: error: Incompatible types in assignment (expression has type "object", variable has type "Type[SentenceTransformer]")  [assignment]
  ```
  
  =>
  
  https://github.com/graphistry/pygraphistry/blob/53448d4ef153fd262466087a951bc28a44c8fadf/graphistry/feature_utils.py#L39
  
  on
  
  ```python
  
  if TYPE_CHECKING:
      MIXIN_BASE = ComputeMixin
      try:
          from sklearn.pipeline import Pipeline
      except:
          Pipeline = Any
      try:
          from sentence_transformers import SentenceTransformer
      except:
          SentenceTransformer = Any
      try:
          from dirty_cat import (
              SuperVectorizer,
              GapEncoder,
              SimilarityEncoder,
          )
      except:
          SuperVectorizer = Any
          GapEncoder = Any
          SimilarityEncoder = Any
      try:
          from sklearn.preprocessing import FunctionTransformer
          from sklearn.base import BaseEstimator, TransformerMixin
      except:
          FunctionTransformer = Any
          BaseEstimator = object
          TransformerMixin = object
  else:
      MIXIN_BASE = object
      Pipeline = Any
      SentenceTransformer = Any
      SuperVectorizer = Any
      GapEncoder = Any
      SimilarityEncoder = Any
      FunctionTransformer = Any
      BaseEstimator = Any
      TransformerMixin = Any
  ```
  
  @tanmoyio @mj3cheun @silkspace can one of you take?