Upgrade to a new Bazel version

This one has better performance and various new features. It also
prevents us from falling too far behind upstream.

Change-Id: I3b8e1c5bda886ea2e990523af9e6de2434c784be
diff --git a/frc971/control_loops/BUILD b/frc971/control_loops/BUILD
index 9dee424..b5f4060 100644
--- a/frc971/control_loops/BUILD
+++ b/frc971/control_loops/BUILD
@@ -14,6 +14,7 @@
     '//aos/common/network:team_number',
     '//aos/testing:googletest',
   ],
+  testonly = True,
 )
 
 cc_test(