Update serialization version for ILM explain filters

Author: gwbrown

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/indexlifecycle/ExplainLifecycleRequest.java

@@ -23,7 +23,7 @@
  * {@link #indices(String...)} method
  */
 public class ExplainLifecycleRequest extends ClusterInfoRequest<ExplainLifecycleRequest> {
-    private static final Version FILTERS_INTRODUCED_VERSION = Version.V_8_0_0;
+    private static final Version FILTERS_INTRODUCED_VERSION = Version.V_7_4_0;
 
     private boolean onlyErrors = false;
     private boolean onlyManaged = false;