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/y2020/actors/autonomous_actor.h b/y2020/actors/autonomous_actor.h
index abf9ea0..9368a8e 100644
--- a/y2020/actors/autonomous_actor.h
+++ b/y2020/actors/autonomous_actor.h
@@ -11,8 +11,7 @@
 #include "y2020/control_loops/superstructure/superstructure_goal_generated.h"
 #include "y2020/control_loops/superstructure/superstructure_status_generated.h"
 
-namespace y2020 {
-namespace actors {
+namespace y2020::actors {
 
 using frc971::control_loops::StaticZeroingSingleDOFProfiledSubsystemGoal;
 
@@ -104,7 +103,6 @@
   std::optional<Eigen::Vector3d> starting_position_;
 };
 
-}  // namespace actors
-}  // namespace y2020
+}  // namespace y2020::actors
 
 #endif  // y2020_ACTORS_AUTONOMOUS_ACTOR_H_