tour: update to new favicon.ico

Change favicon.ico to newer high resolution version from main project.

Change-Id: Iba9a5b13cb9615eaf10167a531065b9f8e101a71
Reviewed-on: https://go-review.googlesource.com/c/148037
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

static/img/favicon.ico

diff --git a/static/img/favicon.ico b/static/img/favicon.ico
index d287722..8d22584 100644
--- a/static/img/favicon.ico
+++ b/static/img/favicon.ico
Binary files differ