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 -Walways -m py_compile {}

./jieba/__init__.py:44: DeprecationWarning: invalid escape sequence \.
  re_han_default = re.compile("([\u4E00-\u9FD5a-zA-Z0-9+#&\._%\-]+)", re.U)
./jieba/__init__.py:46: DeprecationWarning: invalid escape sequence \s
  re_skip_default = re.compile("(\r\n|\s)", re.U)
./jieba/posseg/__init__.py:16: DeprecationWarning: invalid escape sequence \.
  re_skip_detail = re.compile("([\.0-9]+|[a-zA-Z0-9]+)")
./jieba/posseg/__init__.py:17: DeprecationWarning: invalid escape sequence \.
  re_han_internal = re.compile("([\u4E00-\u9FD5a-zA-Z0-9+#&\._]+)")
./jieba/posseg/__init__.py:18: DeprecationWarning: invalid escape sequence \s
  re_skip_internal = re.compile("(\r\n|\s)")
./jieba/posseg/__init__.py:21: DeprecationWarning: invalid escape sequence \.
  re_num = re.compile("[\.0-9]+")
./jieba/finalseg/__init__.py:78: DeprecationWarning: invalid escape sequence \.
  re_skip = re.compile("([a-zA-Z0-9]+(?:\.\d+)?%?)")