style: CDN provider remove GitHub option in settings page

Author: zhangshiliu

src/views/settings/settings.vue

@@ -45,7 +45,6 @@
           <el-option label="Staticaly" value="staticaly"></el-option>
           <el-option label="Cloudflare" value="cloudflare"></el-option>
           <el-option label="jsDelivr" value="jsdelivr"></el-option>
-          <el-option label="GitHub" value="github"></el-option>
         </el-select>
       </li>
     </ul>