Update to 1.43
    
    - New upstream release 1.43
      - Added a small optimization for boolification overloading: rather than
        relying on a fallback to stringification, we now return true directly,
        which is a little faster in cases like "if ($might_be_dt) { ... }"
      - The datetime() method now accepts a single argument to use as the separator
        between the date and time portion; this defaults to "T"
    - Drop redundant Group: tag