Add badges to README.md

Author: bjoern-hempel

README.md

@@ -1,9 +1,14 @@
 # PHP Date Parser
 
 [![Release](https://img.shields.io/github/v/release/ixnode/php-date-parser)](https://github.com/ixnode/php-date-parser/releases)
+[![](https://img.shields.io/github/release-date/ixnode/php-date-parser)](https://github.com/ixnode/php-date-parser/releases)
+![](https://img.shields.io/github/repo-size/ixnode/php-date-parser.svg)
 [![PHP](https://img.shields.io/badge/PHP-^8.2-777bb3.svg?logo=php&logoColor=white&labelColor=555555&style=flat)](https://www.php.net/supported-versions.php)
-[![PHPStan](https://img.shields.io/badge/PHPStan-Level%20Max-brightgreen.svg?style=flat)](https://phpstan.org/user-guide/rule-levels)
-[![PHPCS](https://img.shields.io/badge/PHPCS-PSR12-brightgreen.svg?style=flat)](https://www.php-fig.org/psr/psr-12/)
+[![PHPStan](https://img.shields.io/badge/PHPStan-Level%20Max-777bb3.svg?style=flat)](https://phpstan.org/user-guide/rule-levels)
+[![PHPUnit](https://img.shields.io/badge/PHPUnit-Unit%20Tests-6b9bd2.svg?style=flat)](https://phpunit.de)
+[![PHPCS](https://img.shields.io/badge/PHPCS-PSR12-416d4e.svg?style=flat)](https://www.php-fig.org/psr/psr-12/)
+[![PHPMD](https://img.shields.io/badge/PHPMD-ALL-364a83.svg?style=flat)](https://github.com/phpmd/phpmd)
+[![Rector - Instant Upgrades and Automated Refactoring](https://img.shields.io/badge/Rector-PHP%208.2-73a165.svg?style=flat)](https://github.com/rectorphp/rector)
 [![LICENSE](https://img.shields.io/github/license/ixnode/php-api-version-bundle)](https://github.com/ixnode/php-api-version-bundle/blob/master/LICENSE)
 
 > This library parses various given date and time strings into