Update build_docs.py

Author: MarkDaoust

docs/build_docs.py

@@ -39,6 +39,7 @@
 import jinja2  # must be imported before turning on TYPE_CHECKING
 import pydantic  # must be imported before turning on TYPE_CHECKING
 from IPython import display  # must be imported before turning on TYPE_CHECKING
+import PIL.Image  # must be imported before turning on TYPE_CHECKING
 
 # For showing the conditional imports and types in `content_types.py`
 # grpc must be imported first.