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/y2023/autonomous/autonomous_actor.h b/y2023/autonomous/autonomous_actor.h
index 5a5cd06..829cd0e 100644
--- a/y2023/autonomous/autonomous_actor.h
+++ b/y2023/autonomous/autonomous_actor.h
@@ -11,8 +11,7 @@
 #include "y2023/control_loops/superstructure/superstructure_goal_generated.h"
 #include "y2023/control_loops/superstructure/superstructure_status_generated.h"
 
-namespace y2023 {
-namespace autonomous {
+namespace y2023::autonomous {
 
 class AutonomousActor
     : public ::frc971::autonomous::UserButtonLocalizedAutonomousActor {
@@ -83,7 +82,6 @@
   const ::std::vector<::Eigen::Matrix<double, 3, 1>> points_;
 };
 
-}  // namespace autonomous
-}  // namespace y2023
+}  // namespace y2023::autonomous
 
 #endif  // Y2023_AUTONOMOUS_AUTONOMOUS_ACTOR_H_