Nest some more namespaces

Did someone previously suggest that all namespace had been
nested?  Silly.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I22278c1caaeba8b47dc46fb2ed3078c20a11e190
diff --git a/frc971/wpilib/can_drivetrain_writer.h b/frc971/wpilib/can_drivetrain_writer.h
index 1c0ba95..987605d 100644
--- a/frc971/wpilib/can_drivetrain_writer.h
+++ b/frc971/wpilib/can_drivetrain_writer.h
@@ -3,8 +3,7 @@
 #include "frc971/wpilib/loop_output_handler.h"
 #include "frc971/wpilib/talonfx.h"
 
-namespace frc971 {
-namespace wpilib {
+namespace frc971::wpilib {
 
 class CANDrivetrainWriter : public ::frc971::wpilib::LoopOutputHandler<
                                 ::frc971::control_loops::drivetrain::Output> {
@@ -30,5 +29,4 @@
   std::vector<std::shared_ptr<TalonFX>> left_talonfxs_;
 };
 
-}  // namespace wpilib
-}  // namespace frc971
+}  // namespace frc971::wpilib