Python 3.11 complains about invalid escape sequence in `test-suite/tools/parsers/parse_wpout.py`

[merkys]

Multiple SyntaxWarnings are thrown from test-suite/tools/parsers/parse_wpout.py when running tests with Python 3.11, for example:

test-suite/tools/parsers/parse_wpout.py:16:
SyntaxWarning: invalid escape sequence '\s'
near_neigh_re = re.compile("^\s*\|\s+(\d+)\s+([\d\.]+)\s*(\d+)\s*")