fix SfnClientInstrumentation class header

Author: nhulston

dd-java-agent/instrumentation/aws-java-sfn-2.0/src/main/java/datadog/trace/instrumentation/aws/v2/sfn/SfnClientInstrumentation.java

@@ -13,7 +13,7 @@
 /** AWS SDK v2 Step Function instrumentation */
 @AutoService(InstrumenterModule.class)
 public final class SfnClientInstrumentation extends InstrumenterModule.Tracing
-    implements Instrumenter.ForSingleType {
+    implements Instrumenter.ForSingleType, Instrumenter.HasMethodAdvice {
 
   public SfnClientInstrumentation() {
     super("sfn", "aws-sdk");