Fix TQDM usage (#465)

Newer versions of tqdm behave differently at a terminal vs in a jupyter
notebook. Import from `tqdm.auto` instead so that the downloader looks
right in either a notebook or the terminal.

Author: danshapero

pooch/downloaders.py

@@ -19,7 +19,7 @@
 # Mypy doesn't like assigning None like this.
 # Can just use a guard variable
 try:
-    from tqdm import tqdm
+    from tqdm.auto import tqdm
 except ImportError:
     tqdm = None  # type: ignore