Make router base generic

nuxt.config.js

 import pkg from './package'
 
+const { CI_PAGES_URL } = process.env
+const base = CI_PAGES_URL && new URL(CI_PAGES_URL).pathname
+
 export default {
   mode: 'universal',
 
@@ -34,7 +37,7 @@ export default {
   ** Customize the base url
   */
   router: {
-    base: '/nuxt/'
+    base
   },
 
   /*