Remove incorrect linux icon config to fix linux app no icon issue

According to the official electron-builder doc:

> Linux icon set will be generated automatically based on the macOS
> `icns` file or common `icon.png`.
>
> Or you can put them into the `build/icons` directory if you want to
> specify them yourself.
> The filename must contain the size (e.g. `256x256.png`) of the icon).
> Recommended sizes: 16, 32, 48, 64, 128, 256 (or just 512).

The old config is somehow wrong.

Reference:
- https://www.electron.build/icons#linux

vue.config.js

@@ -32,7 +32,6 @@ module.exports = defineConfig({
         },
         linux: {
           target: ["AppImage", "deb"],
-          icon: "src/assets/icon.png",
         },
         nsis: {
           oneClick: false,