[Elixir] update to 1.6 version (#2741)

* [Elixir] update version / add test

* update samples (add missing 200 responses in petstore-with-fake-endpoints-models-for-testing.yaml)

* [Elixir] update to 1.6 version

* [Elixir] fix test petapi

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/api/PetApi.java

@@ -51,6 +51,7 @@ public class PetApi {
     /**
      * Add a new pet to the store
      * 
+     * <p><b>200</b> - successful operation
      * <p><b>405</b> - Invalid input
      * @param body Pet object that needs to be added to the store
      * @throws RestClientException if an error occurs while attempting to invoke the API
@@ -84,6 +85,7 @@ public class PetApi {
     /**
      * Deletes a pet
      * 
+     * <p><b>200</b> - successful operation
      * <p><b>400</b> - Invalid pet value
      * @param petId Pet id to delete
      * @param apiKey The apiKey parameter
@@ -235,6 +237,7 @@ public class PetApi {
     /**
      * Update an existing pet
      * 
+     * <p><b>200</b> - successful operation
      * <p><b>400</b> - Invalid ID supplied
      * <p><b>404</b> - Pet not found
      * <p><b>405</b> - Validation exception