Invalid escape sequences in Regexes cause SyntaxWarnings in Python >=3.12

[Ferdi265]

When using latexrun with Python 3.12 and up, this gets printed every run:

/usr/bin/latexrun:1214: SyntaxWarning: invalid escape sequence '\w'
  if lookingatre('(Package |Class |LaTeX |pdfTeX )?(\w+ )?warning: ', re.I):
/usr/bin/latexrun:1353: SyntaxWarning: invalid escape sequence '\.'
  m2 = self.__lookingatre('l\.[0-9]+ ')
/usr/bin/latexrun:1849: SyntaxWarning: invalid escape sequence '\d'
  m2 = re.match("BibTeX subsystem: (.*?), line (\d+), (.*)$", m.group(1))

This is caused by invalid escape sequences in regexes. The solution is to use raw strings for these regexes as well.