Chart.yaml: Update icon URL

Signed-off-by: Gary Edgar <gary@planetscale.com>

helm/vitess/Chart.yaml

@@ -17,4 +17,4 @@ sources:
 maintainers:
   - name: Vitess Project
     email: vitess@googlegroups.com
-icon: https://vitess.io/images/vitess_logo_with_border.svg
+icon: https://vitess.io/img/logos/vitess.png