Import collection ABCs from new path

Importing the Iterable, Sequence, and Mapping ABCs directly from
collections was deprecated in Python 3.3 and the aliases were removed in
Python 3.10.

Attempt to import from the new location, but if it fails because the
current Python is older than 3.3, fall back to the old location.

Author: gmacon

src/bap/adt.py

@@ -182,7 +182,10 @@ def count_authors(library):
 
 """
 
-from collections import Iterable,Sequence,Mapping
+try:
+    from collections.abc import Iterable,Sequence,Mapping
+except ImportError:
+    from collections import Iterable,Sequence,Mapping
 
 class ADT(object):
     """Algebraic Data Type.

src/bap/bir.py

@@ -2,7 +2,10 @@
 
 """BIR - BAP Intermediate Representation"""
 
-from collections import Sequence,Mapping
+try:
+    from collections.abc import Sequence,Mapping
+except ImportError:
+    from collections import Sequence,Mapping
 from .adt import *
 from .bil import *
 from . import noeval_parser