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/media_device.h b/frc971/vision/media_device.h
index a2a86fe..31d0882 100644
--- a/frc971/vision/media_device.h
+++ b/frc971/vision/media_device.h
@@ -16,8 +16,7 @@
 
 #include "aos/scoped/scoped_fd.h"
 
-namespace frc971 {
-namespace vision {
+namespace frc971::vision {
 
 class MediaDevice;
 class Pad;
@@ -254,7 +253,6 @@
 // nullopt otherwise.
 std::optional<MediaDevice> FindMediaDevice(std::string_view device);
 
-}  // namespace vision
-}  // namespace frc971
+}  // namespace frc971::vision
 
 #endif  // FRC971_VISION_MEDIA_DEVICE_H_