Fix f37 FTBFS Python 3.11 API incompatibilities
    
    Python 3.11 "ValueError: invalid mode: 'rU'"
    'U' is deprecated since Python 3 and default, error with Python 3.11
    Remove 'U' from '"rU"' to '"r"'.
    
    Python 3.11 "Invalid regular expression for rule '...'.
    global flags not at the start of the expression at position ...
    Change global inline flags (?s)... to local inline flags (?s:...)
    
    See
    https://docs.python.org/3.11/whatsnew/3.11.html#changes-in-the-python-api
    
    * open(), io.open(), codecs.open() and fileinput.FileInput no
      longer accept 'U' (“universal newline”) in the file mode. This
      flag was deprecated since Python 3.3. In Python 3, the
      “universal newline” is used by default when a file is open in
      text mode.
    
    * Global inline flags (e.g. (?i)) can now only be used at the
      start of the regular expressions. Using them not at the start of
      expression was deprecated since Python 3.6.