MAINT: import from collections.abc (#3560)

* MAINT: import from collections.abc

* MAINT: split collections import

Author: andyfaff

pymc3/sampling.py

@@ -2,7 +2,8 @@
 if TYPE_CHECKING:
     from typing import Any
 from typing import Iterable as TIterable
-from collections import defaultdict, Iterable
+from collections.abc import Iterable
+from collections import defaultdict
 from copy import copy
 import pickle
 import logging