appview: do not require auth for upgrade banner

the upgrade banner is left empty if the user's session is expired. this
prevents them from randomly being booted to the login page.

Signed-off-by: oppiliappan <[e-mail]>

appview/state/router.go

···
 
 	r.Get("/", s.HomeOrTimeline)
 	r.Get("/timeline", s.Timeline)
-	r.With(middleware.AuthMiddleware(s.oauth)).Get("/upgradeBanner", s.UpgradeBanner)
+	r.Get("/upgradeBanner", s.UpgradeBanner)
 
 	// special-case handler for serving tangled.org/core
 	r.Get("/core", s.Core())

appview/state/state.go

···
 
 func (s *State) UpgradeBanner(w http.ResponseWriter, r *http.Request) {
 	user := s.oauth.GetUser(r)
+	if user == nil {
+		return
+	}
+
 	l := s.logger.With("handler", "UpgradeBanner")
 	l = l.With("did", user.Did)
 	l = l.With("handle", user.Handle)