Handle more ResourceWarning issues. admin.py - remove unneeded close. mailer.py - close debug log file. indexer.py - close read of version file memorydb.py - close python files being compled. Similiar to instance. not sure why it's compoing things and not just letting instance do it. .travis.ymv disable all except 3.9-dev till we get a handle on errors. also increase errors to 50 from 20.

try:
    # Python 3+.
    from xmlrpc import client, server
    server.SimpleXMLRPCDispatcher
except (ImportError, AttributeError):
    # Python 2.
    import xmlrpclib as client  # noqa: F401
    import SimpleXMLRPCServer as server