Fix too-narrow exception caught in qvm_shutdown

Instead of QubesVMNotStartedError, QubesVMNotRunningError
(which is a subclass) was being caught, which led to
unintended error raised on shutting down an
already-shut down VM.

fixes QubesOS/qubes-issues#3032

qubesadmin/tools/qvm_shutdown.py

@@ -72,7 +72,7 @@ def main(args=None, app=None):  # pylint: disable=missing-docstring
         for vm in this_round_domains:
             try:
                 vm.shutdown(force=force)
-            except qubesadmin.exc.QubesVMNotRunningError:
+            except qubesadmin.exc.QubesVMNotStartedError:
                 pass
             except qubesadmin.exc.QubesException as e:
                 if not args.wait: