Deprecation warning due to invalid escape sequences in Python 3.8

[tirkarthi]

Deprecation warnings are raised due to invalid escape sequences in Python 3.8 . Below is a log of the warnings raised during compiling all the python files. Using raw strings or escaping them will fix this issue.

find . -iname '*.py'  | xargs -P 4 -I{} python -Wall -m py_compile {} 

./usaddress/__init__.py:247: DeprecationWarning: invalid escape sequence \w
  if bool(re.match('.+[^.\w]', token, flags=re.UNICODE))