Fix errors from new cpplint.py (#7105)

wpilibc/src/test/native/cpp/shuffleboard/ShuffleboardInstanceTest.cpp

@@ -11,7 +11,6 @@
 #include <networktables/NetworkTableListener.h>
 #include <networktables/StringTopic.h>
 
-#include "frc/shuffleboard/ShuffleboardInstance.h"
 #include "shuffleboard/MockActuatorSendable.h"
 
 class NTWrapper {

wpilibc/src/test/native/cpp/shuffleboard/SuppliedValueWidgetTest.cpp

@@ -2,6 +2,9 @@
 // Open Source Software; you can modify and/or share it under the terms of
 // the WPILib BSD license file in the root directory of this project.
 
+#include <string>
+#include <vector>
+
 #include <gtest/gtest.h>
 #include <networktables/NetworkTableEntry.h>
 #include <networktables/NetworkTableInstance.h>