Small speedup improvement on the inspection logic in Python

src/inspectorscripts.ts

@@ -152,7 +152,7 @@ def _jupyterlab_variableinspector_dict_list():
  def keep_cond(v):
  try:
  obj = eval(v)
- if isinstance(obj, str):
+ if isinstance(obj, (bool, str, list, int, float, type(None))):
  return True
  if __tf and isinstance(obj, __tf.Variable):
  return True