fix(GroupNavigationItem): encode exported contact groups as UTF-8

Signed-off-by: Grigory Vodyanov <scratchx@gmx.com>

src/components/AppNavigation/GroupNavigationItem.vue

@@ -227,7 +227,8 @@ export default {
 		async downloadVcardPromise(vcardPromise) {
 			vcardPromise.then(response => {
 				const filename = moment().format('YYYY-MM-DD_HH-mm') + '_' + response.groupName + '.vcf'
-				download(response.data, filename, 'text/vcard')
+				const content = 'data:text/plain;charset=utf-8,' + window.encodeURIComponent(response.data)
+				download(content, filename, 'text/vcard')
 			})
 		},