fix: do not show flash message when changing app theme

it is just distracting esp. when testing different themes

tailbone/views/common.py

@@ -151,8 +151,6 @@ class CommonView(View):
             except Exception as error:
                 msg = "Failed to set theme: {}: {}".format(error.__class__.__name__, error)
                 self.request.session.flash(msg, 'error')
-            else:
-                self.request.session.flash("App theme has been changed to: {}".format(theme))
         referrer = self.request.params.get('referrer') or self.request.get_referrer()
         return self.redirect(referrer)