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/y2023_bot3/autonomous/auto_splines.cc b/y2023_bot3/autonomous/auto_splines.cc
index 25277e9..b0577bf 100644
--- a/y2023_bot3/autonomous/auto_splines.cc
+++ b/y2023_bot3/autonomous/auto_splines.cc
@@ -3,8 +3,7 @@
 #include "aos/flatbuffer_merge.h"
 #include "frc971/control_loops/control_loops_generated.h"
 
-namespace y2023_bot3 {
-namespace autonomous {
+namespace y2023_bot3::autonomous {
 
 namespace {
 flatbuffers::Offset<frc971::MultiSpline> FixSpline(
@@ -172,5 +171,4 @@
   return FixSpline(builder, multispline_builder.Finish(), alliance);
 }
 
-}  // namespace autonomous
-}  // namespace y2023_bot3
+}  // namespace y2023_bot3::autonomous