Fixes duplicate alias that fails npm run compile

Fixes issue when running `npm run compile`

```
examples/ufm-custom-component/index.ts:12:4 - error TS1117: An object literal cannot have multiple properties with the same name.

12    alias: 'myCustomComponent',
      ~~~~~


Found 1 error in examples/ufm-custom-component/index.ts:12
```

src/Umbraco.Web.UI.Client/examples/ufm-custom-component/index.ts

@@ -8,8 +8,7 @@ export const manifests: Array<ManifestUfmComponent> = [
 		api: () => import('./custom-ufm-component.js'),
 		meta: {
 			alias: 'myCustomComponent',
-			marker: '%',
-			alias: 'myCustomComponent',
+			marker: '%'
 		},
 	},
 ];