Update 2020 wpilib_interface.

Also remove an unused output field.

Change-Id: I9721fe923104b48984ab5895e28ef111c810d611
diff --git a/y2020/BUILD b/y2020/BUILD
index f0f87d2..79dc651 100644
--- a/y2020/BUILD
+++ b/y2020/BUILD
@@ -76,6 +76,7 @@
         "//frc971/wpilib:sensor_reader",
         "//frc971/wpilib:wpilib_interface",
         "//frc971/wpilib:wpilib_robot_base",
+        "//third_party:phoenix",
         "//third_party:wpilib",
         "//y2020/control_loops/superstructure:superstructure_output_fbs",
         "//y2020/control_loops/superstructure:superstructure_position_fbs",