Adds Envoy gateway 1.4.0 and 1.5.0 (#534)

* add support for envoy-gateway 1.1.0

* Add Envoy Gateway 1.2.1

* Add envoy-gateway v1.3.0

* remove EOL'd versions

* Add envoy-gateway v1.4.0

* Add envoy gateway 1.5.0

Author: vtomasr5

libs/envoy-gateway/config.jsonnet

@@ -1,5 +1,5 @@
 local config = import 'jsonnet/config.jsonnet';
-local versions = ['v1.2.1', 'v1.3.0'];
+local versions = ['v1.3.0', 'v1.4.0', 'v1.5.0'];
 
 config.new(
   name='envoy-gateway',