Remove copy of Values in wpilib_interface

Auto was hiding a copy...  Gotta love auto.

Change-Id: I27fb9835ca39b1f80898dad71c7835187bf04a86
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/y2020/wpilib_interface.cc b/y2020/wpilib_interface.cc
index 217c6b7..b8def33 100644
--- a/y2020/wpilib_interface.cc
+++ b/y2020/wpilib_interface.cc
@@ -238,7 +238,7 @@
 
       builder.Send(drivetrain_builder.Finish());
     }
-    const auto values = constants::GetValues();
+    const constants::Values &values = constants::GetValues();
 
     {
       auto builder = superstructure_position_sender_.MakeBuilder();