Replaced lxml library with standard lib xml library

[jacobamarshall]

Replaced lxml library with standard lib xml library
Reformatted code with Black (https://pypi.org/project/black/)

Description

Updated imports and replaced all Element.getparent() and Element.index()
calls with other logic to retrieve parent elements

Motivation and Context

lxml poses challenges when using this library in aws lambda environments,
and standard lib is preferable when available

How Has This Been Tested?

All tests ran successfully with %python -m unittest discover

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.