Remove unstable version badge from README

Removed the unstable version badge from the README.

Author: andrey-helldar

README.md

@@ -3,7 +3,6 @@
 ![laravel-lang native locale names](https://preview.dragon-code.pro/laravel-lang/native-locale-names.svg?brand=laravel&mode=dark)
 
 [![Stable Version][badge_stable]][link_packagist]
-[![Unstable Version][badge_unstable]][link_packagist]
 [![Total Downloads][badge_downloads]][link_packagist]
 [![License][badge_license]][link_license]
 
@@ -26,8 +25,6 @@ This package is licensed under the [MIT License](https://laravel-lang.com/licens
 
 [badge_stable]:     https://img.shields.io/github/v/release/Laravel-Lang/native-locale-names?label=stable&style=flat-square
 
-[badge_unstable]:   https://img.shields.io/badge/unstable-dev--main-orange?style=flat-square
-
 [badge_downloads]:  https://img.shields.io/packagist/dt/Laravel-Lang/native-locale-names.svg?style=flat-square
 
 [badge_license]:    https://img.shields.io/packagist/l/Laravel-Lang/native-locale-names.svg?style=flat-square