Nest all namespaces

The compiler supports this now.  We can type less going forward.
No functional changes.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I29d6fa4f9aacc0e381f1a7637294db0392466995
diff --git a/y2022/actors/auto_splines.cc b/y2022/actors/auto_splines.cc
index e674dc4..b0915d5 100644
--- a/y2022/actors/auto_splines.cc
+++ b/y2022/actors/auto_splines.cc
@@ -2,8 +2,7 @@
 
 #include "frc971/control_loops/control_loops_generated.h"
 
-namespace y2022 {
-namespace actors {
+namespace y2022::actors {
 
 void MaybeFlipSpline(
     aos::Sender<frc971::control_loops::drivetrain::Goal>::Builder *builder,
@@ -100,5 +99,4 @@
       alliance);
 }
 
-}  // namespace actors
-}  // namespace y2022
+}  // namespace y2022::actors