py-guppy3: update to 3.1.0

Change log:

Version 3.1.0

    * Python 3.9 support, no inter-interpreter support
    * Add R_INSET relation for in unordered set relationship
    * Unified MorePrinter code path
    * Set __qualname__ to __name__ on dynamic classes
    * hp.Prod(), .byprod classifier, producer profiler
    * IdentitySet.prod to print tracemalloc results
    * Add .all to MorePrinter

(gutteridge)