autoswitch tqdm for notebooks (lucidrains#171)

avoids printing the `tqdm` progress bar to a newline in notebooks when detected

dalle2_pytorch/dalle2_pytorch.py

@@ -1,6 +1,6 @@
 import math
 import random
-from tqdm import tqdm
+from tqdm.auto import tqdm
 from functools import partial, wraps
 from contextlib import contextmanager
 from collections import namedtuple