Support old and new collections.abc.Sequence (#745)

Addresses #744

Author: timgates42

gspread/utils.py

@@ -11,7 +11,11 @@
 import sys
 import re
 from functools import wraps
-from collections import defaultdict, Sequence
+from collections import defaultdict
+try:
+    from collections.abc import Sequence
+except ImportError:
+    from collections import Sequence
 from itertools import chain
 
 from .exceptions import IncorrectCellLabel, NoValidUrlKeyFound