Fixes #4500, collections depreciated (#4541)

* Fixes #4500, collections depreciation

Collections will be removed as of Python 3.10, Added Compatibility for versions < 3.3.

* Added Depreciation Check for Python 3.3+

* Removed if/else, added try/except

* Remove unused 'sys' library (whoops)

kitsune/wiki/widgets.py

@@ -1,11 +1,15 @@
-import collections
 
 from django import forms
 from django.template.loader import render_to_string
 
 from kitsune.products.models import Topic
 from kitsune.wiki.models import Document
 
+try:
+    from collections.abc import Iterable
+except ImportError:
+    from collections import Iterable
+
 
 class ProductTopicsAndSubtopicsWidget(forms.widgets.SelectMultiple):
     """A widget to render topics organized by product and with subtopics."""
@@ -35,7 +39,7 @@ def process_topic(self, value, topic):
             topic.checked = True
         elif (
             not isinstance(value, str)
-            and isinstance(value, collections.Iterable)
+            and isinstance(value, Iterable)
             and topic.id in value
         ):
             topic.checked = True
@@ -49,7 +53,7 @@ class RelatedDocumentsWidget(forms.widgets.SelectMultiple):
     def render(self, name, value, attrs=None, renderer=None):
         if isinstance(value, int):
             related_documents = Document.objects.filter(id__in=[value])
-        elif not isinstance(value, str) and isinstance(value, collections.Iterable):
+        elif not isinstance(value, str) and isinstance(value, Iterable):
             related_documents = Document.objects.filter(id__in=value)
         else:
             related_documents = Document.objects.none()