Update stable tag

Author: swissspidy

readme.txt

@@ -2,7 +2,7 @@
 Contributors: swissspidy
 Tags: internationalization, i18n, localization, l10n, language, locale, translation
 Tested up to: 5.8
-Stable tag: 1.7.1
+Stable tag: 1.8.0
 License: GPLv2 or later
 License URI: http://www.gnu.org/licenses/gpl-2.0.html