chore: update sponsor link (#2026)

Co-authored-by: Evan You <yyx990803@gmail.com>

Author: vuejs-jp-bot

themes/vue/_config.yml

@@ -97,7 +97,7 @@ gold_sponsors:
   - url: 'https://unicorn.io/'
     img: unicorn_io.png
     name: Unicorn.io
-  - url: 'https://www.programmers.io'
+  - url: 'https://www.programmers.io/vuejs/'
     img: programmers_io.png
     name: Programmers.io
   - url: 'https://www.vuescreencasts.com/'