Use nested namespace

It's a mechanical change to modernize the code base

unit_tests/mocks/mock_datafacade.hpp

@@ -19,9 +19,7 @@
 #include "util/guidance/entry_class.hpp"
 #include "util/typedefs.hpp"
 
-namespace osrm
-{
-namespace test
+namespace osrm::test
 {
 
 class MockBaseDataFacade : public engine::datafacade::BaseDataFacade
@@ -260,7 +258,6 @@ class MockDataFacade final : public MockBaseDataFacade, public MockAlgorithmData
 {
 };
 
-} // namespace test
 } // namespace osrm
 
 #endif // MOCK_DATAFACADE_HPP

unit_tests/mocks/mock_scripting_environment.hpp

@@ -11,10 +11,7 @@
 #include <utility>
 #include <vector>
 
-namespace osrm
-{
-
-namespace test
+namespace osrm::test
 {
 
 // a mock implementation of the scripting environment doing exactly nothing
@@ -50,7 +47,6 @@ class MockScriptingEnvironment : public extractor::ScriptingEnvironment
     bool HasLocationDependentData() const override { return false; };
 };
 
-} // namespace test
 } // namespace osrm
 
 #endif // MOCK_SCRIPTING_ENVIRONMENT_HPP_