Update Gateway API version badge for Traefik Proxy (#4224)

Author: nmengin

site-src/implementations.md

@@ -600,7 +600,7 @@ STUNner currently supports version `v1alpha2` of the Gateway API specification.
 
 ### Traefik Proxy
 
-[![Conformance](https://img.shields.io/badge/Gateway%20API%20Conformance%20v1.3.0-Traefik Proxy-green)](https://github.com/kubernetes-sigs/gateway-api/blob/main/conformance/reports/v1.3.0/traefik-traefik)
+[![Conformance](https://img.shields.io/badge/Gateway%20API%20Conformance%20v1.4.0-Traefik Proxy-green)](https://github.com/kubernetes-sigs/gateway-api/blob/main/conformance/reports/v1.4.0/traefik-traefik)
 
 [Traefik Proxy][traefik-proxy] is an open source cloud-native application proxy.