docs: nginx badge 1.21.4 -> 1.21.5

README.md

@@ -1,6 +1,6 @@
 [![Test](https://github.com/nginx-proxy/nginx-proxy/actions/workflows/test.yml/badge.svg)](https://github.com/nginx-proxy/nginx-proxy/actions/workflows/test.yml)
 [![GitHub release](https://img.shields.io/github/v/release/nginx-proxy/nginx-proxy)](https://github.com/nginx-proxy/nginx-proxy/releases)
-![nginx 1.21.4](https://img.shields.io/badge/nginx-1.21.4-brightgreen.svg)
+![nginx 1.21.5](https://img.shields.io/badge/nginx-1.21.5-brightgreen.svg)
 [![Docker Image Size](https://img.shields.io/docker/image-size/nginxproxy/nginx-proxy?sort=semver)](https://hub.docker.com/r/nginxproxy/nginx-proxy "Click to view the image on Docker Hub")
 [![Docker stars](https://img.shields.io/docker/stars/nginxproxy/nginx-proxy.svg)](https://hub.docker.com/r/nginxproxy/nginx-proxy 'DockerHub')
 [![Docker pulls](https://img.shields.io/docker/pulls/nginxproxy/nginx-proxy.svg)](https://hub.docker.com/r/nginxproxy/nginx-proxy 'DockerHub')