Fix Run in Colab thumbnails blocked by CSP (#37838)

Author: aIbrahiim

website/www/site/layouts/shortcodes/button-colab.html

@@ -14,7 +14,7 @@
   <td>
     <a class="button" target="_blank" href="{{ .Get `url` }}">
       <img alt="Run in Colab" width="32px" height="32px"
-        src="https://github.com/googlecolab/open_in_colab/raw/master/images/icon32.png" />
+        src="/images/colab/icon32.png" />
       Run in Colab
     </a>
   </td>