fix: resolve SyntaxWarning from invalid escape sequences

[Aalivexy]

/usr/lib/python3.12/site-packages/demos/歌单同步.py:1: SyntaxWarning: invalid escape sequence '\d'
/usr/lib/python3.12/site-packages/demos/歌单同步.py:1: SyntaxWarning: invalid escape sequence '\d'
/usr/lib/python3.12/site-packages/pyncm/__main__.py:474: SyntaxWarning: invalid escape sequence '\/'
/usr/lib/python3.12/site-packages/pyncm/__main__.py:477: SyntaxWarning: invalid escape sequence '\d'
/usr/lib/python3.12/site-packages/pyncm/__main__.py:474: SyntaxWarning: invalid escape sequence '\/'
/usr/lib/python3.12/site-packages/pyncm/__main__.py:477: SyntaxWarning: invalid escape sequence '\d'

A backslash-character pair that is not a valid escape sequence now generates a SyntaxWarning, instead of DeprecationWarning. For example, re.compile("\d+.\d+") now emits a SyntaxWarning ("\d" is an invalid escape sequence, use raw strings for regular expression: re.compile(r"\d+.\d+")). In a future Python version, SyntaxError will eventually be raised, instead of SyntaxWarning. (Contributed by Victor Stinner in gh-98401.)

ref: https://docs.python.org/dev/whatsnew/3.12.html#other-language-changes

[mos9527]

LGTM! Merging now.