Deprecation warning due to invalid escape sequences in Python 3.8

Created by: 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 {}

./pyod/models/cblof.py:27: DeprecationWarning: invalid escape sequence \|
  """The CBLOF operator calculates the outlier score based on cluster-based
./pyod/models/xgbod.py:31: DeprecationWarning: invalid escape sequence \*
  """XGBOD class for outlier detection.