Warnings in Python 3.8

[tirkarthi]

• Deprecation warnings are raised due to invalid escape sequences. This can be fixed by using raw strings or escaping the literals. pyupgrade also helps in automatic conversion : https://github.com/asottile/pyupgrade/
• Syntax warning over comparison of literals using is.

find . -iname '*.py' | grep -v example | xargs -P4 -I{} python3.8 -Wall -m py_compile {}
./flask_restful_swagger/swagger.py:528: DeprecationWarning: invalid escape sequence \(
  path = re.sub('\([^\)]*\)', '', path)
./flask_restful_swagger/swagger.py:317: SyntaxWarning: "is not" with a literal. Did you mean "!="?
  if op.get(att_name) and att_name is not 'nickname':