scripts/qmp-shell: fix connect method signature

It needs to match the parent's signature -- the negotiate parameter must
be optional.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210607200649.1840382-6-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

scripts/qmp/qmp-shell

@@ -278,7 +278,7 @@ class QMPShell(qmp.QEMUMonitorProtocol):
         self._print(resp)
         return True
 
-    def connect(self, negotiate):
+    def connect(self, negotiate: bool = True):
         self._greeting = super(QMPShell, self).connect(negotiate)
         self.__completer_setup()