update collections for python3.10

docx/section.py

@@ -6,14 +6,15 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
-from collections import Sequence
+from collections.abc import Sequence
 
 
 class Sections(Sequence):
  """
  Sequence of |Section| objects corresponding to the sections in the
  document. Supports ``len()``, iteration, and indexed access.
  """
+
  def __init__(self, document_elm):
  super(Sections, self).__init__()
  self._document_elm = document_elm
@@ -37,6 +38,7 @@ class Section(object):
  """
  Document section, providing access to section and page setup settings.
  """
+
  def __init__(self, sectPr):
  super(Section, self).__init__()
  self._sectPr = sectPr