[wpimath] TrapezoidProfile.State implement StructSerializable (wpilibsuite#8499)

Seems like this was missed in wpilibsuite#8163

Author: bryceroethel

wpimath/src/main/java/edu/wpi/first/math/trajectory/TrapezoidProfile.java

@@ -7,6 +7,7 @@
 import edu.wpi.first.math.MathSharedStore;
 import edu.wpi.first.math.MathUsageId;
 import edu.wpi.first.math.trajectory.struct.TrapezoidProfileStateStruct;
+import edu.wpi.first.util.struct.StructSerializable;
 import java.util.Objects;
 
 /**
@@ -76,7 +77,7 @@ public Constraints(double maxVelocity, double maxAcceleration) {
   }
 
   /** Profile state. */
-  public static class State {
+  public static class State implements StructSerializable {
     /** The struct used to serialize this class. */
     public static final TrapezoidProfileStateStruct struct = new TrapezoidProfileStateStruct();