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/aos/network/team_number_test.cc b/aos/network/team_number_test.cc
index 68727e2..1ca3fc2 100644
--- a/aos/network/team_number_test.cc
+++ b/aos/network/team_number_test.cc
@@ -2,9 +2,7 @@
 
 #include "gtest/gtest.h"
 
-namespace aos {
-namespace network {
-namespace testing {
+namespace aos::network::testing {
 
 using team_number_internal::ParsePiTeamNumber;
 using team_number_internal::ParseRoborioTeamNumber;
@@ -49,6 +47,4 @@
   EXPECT_FALSE(ParsePiNumber("pi-971"));
 }
 
-}  // namespace testing
-}  // namespace network
-}  // namespace aos
+}  // namespace aos::network::testing