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/frc971/vision/intrinsics_calibration_lib.cc b/frc971/vision/intrinsics_calibration_lib.cc
index 6cf53e8..ab03e01 100644
--- a/frc971/vision/intrinsics_calibration_lib.cc
+++ b/frc971/vision/intrinsics_calibration_lib.cc
@@ -1,7 +1,6 @@
 #include "frc971/vision/intrinsics_calibration_lib.h"
 
-namespace frc971 {
-namespace vision {
+namespace frc971::vision {
 
 IntrinsicsCalibration::IntrinsicsCalibration(
     aos::EventLoop *event_loop, std::string_view pi, std::string_view camera_id,
@@ -241,5 +240,4 @@
     LOG(INFO) << "Skipping calibration due to not enough images.";
   }
 }
-}  // namespace vision
-}  // namespace frc971
+}  // namespace frc971::vision