Use fixed version for mailhog

Author: Jan Raap

modules/mailhog/src/main/java/org/testcontainers/containers/MailHogContainer.java

@@ -23,7 +23,7 @@
  */
 public class MailHogContainer extends GenericContainer<MailHogContainer> {
 
-    private static final String VERSION = "latest";
+    private static final String VERSION = "v1.0.1";
 
     public static final int SMTP_PORT = 1025;
     public static final int HTTP_PORT = 8025;