Update to the multi-platform gesellix/echo-server image

Author: gesellix

api-client/src/test/java/de/gesellix/docker/remote/api/testutil/TestImage.java

@@ -16,7 +16,7 @@ public TestImage(EngineApiClient engineApiClient) {
 
     this.useWindowsContainer = Objects.requireNonNull(engineApiClient.getSystemApi().systemVersion().getOs()).equalsIgnoreCase("windows");
     this.repository = "gesellix/echo-server";
-    this.tag = useWindowsContainer ? "os-windows" : "os-linux";
+    this.tag = "2022-04-08T22-27-00";
 
     // TODO consider NOT calling prepare inside the constructor
     prepare();