FEATURE (readme): Add PostgreSQL 18 label [skip-release]

Author: RostislavDugin

README.md

@@ -9,7 +9,7 @@
   [![Docker Pulls](https://img.shields.io/docker/pulls/rostislavdugin/postgresus?color=brightgreen)](https://hub.docker.com/r/rostislavdugin/postgresus)
   [![Platform](https://img.shields.io/badge/platform-linux%20%7C%20macos%20%7C%20windows-lightgrey)](https://github.com/RostislavDugin/postgresus)
 
-  [![PostgreSQL](https://img.shields.io/badge/PostgreSQL-13%20%7C%2014%20%7C%2015%20%7C%2016%20%7C%2017-336791?logo=postgresql&logoColor=white)](https://www.postgresql.org/)
+  [![PostgreSQL](https://img.shields.io/badge/PostgreSQL-13%20%7C%2014%20%7C%2015%20%7C%2016%20%7C%2017%20%7C%2018-336791?logo=postgresql&logoColor=white)](https://www.postgresql.org/)
   [![Self Hosted](https://img.shields.io/badge/self--hosted-yes-brightgreen)](https://github.com/RostislavDugin/postgresus)
   [![Open Source](https://img.shields.io/badge/open%20source-❤️-red)](https://github.com/RostislavDugin/postgresus)