fix(v-btn): added missing component import
fix(v-btn): added missing component import

`v-btn` was not properly importing `v-progress-circular`, causing errors in a-la-carte

fixes #3391

vuetifyjs/vuetify,Webifi/vuetify,Phlow2001/vuetify,Phlow2001/vuetify,Webifi/vuetify,vuetifyjs/vuetify,Phlow2001/vuetify,vuetifyjs/vuetify,vuetifyjs/vuetify,Webifi/vuetify,Phlow2001/vuetify