Deprecation warning due to invalid escape sequences in Python 3.8

[tirkarthi]

Environment

• Python version: 3.8
• PyKwalify version: master branch

Steps to Reproduce

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 {} 

./pykwalify/types.py:162: DeprecationWarning: invalid escape sequence \(
  return re.match('http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+', obj)

[andrewshadura]

Hi @Grokzen, could you please look at this?