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/frc971/vision/charuco_lib.h b/frc971/vision/charuco_lib.h
index 62923db..aac25ee 100644
--- a/frc971/vision/charuco_lib.h
+++ b/frc971/vision/charuco_lib.h
@@ -17,8 +17,7 @@
 
 DECLARE_bool(visualize);
 
-namespace frc971 {
-namespace vision {
+namespace frc971::vision {
 
 // Class to find extrinsics for a specified pi's camera using the provided
 // training data.
@@ -211,7 +210,6 @@
     const foxglove::PointsAnnotationType line_type =
         foxglove::PointsAnnotationType::POINTS);
 
-}  // namespace vision
-}  // namespace frc971
+}  // namespace frc971::vision
 
 #endif  // Y2020_VISION_CHARUCO_LIB_H_