Update Python scripts to heed new warning
Python 3.12 yields messages such as:
/builds/2mk6rsew/0/sgilles/MoReFEM/build/../cmake/Scripts/configure_cmake.py:34: SyntaxWarning: invalid escape sequence '\p'
"""Interpret the content of the command line.
This blog post explains the reasons; present ticket aims to fix them as Python 3.13 should outright fail due to this syntax to correct.