Update tests to the latest oatpp 1.4.0 API

[hugoaboud]

I've followed the README instructions and had the following errors:

[ 87%] Building CXX object CMakeFiles/hls-example-test.dir/test/tests.cpp.o
/home/aboud/sandbox/example-hls-media-stream/test/tests.cpp: In member function ‘virtual void {anonymous}::Test::onRun()’:
/home/aboud/sandbox/example-hls-media-stream/test/tests.cpp:13:5: error: ‘OATPP_LOGD’ was not declared in this scope; did you mean ‘OATPP_LOGd’?
   13 |     OATPP_LOGD(TAG, "Hello Test");
      |     ^~~~~~~~~~
      |     OATPP_LOGd
/home/aboud/sandbox/example-hls-media-stream/test/tests.cpp: In function ‘int main()’:
/home/aboud/sandbox/example-hls-media-stream/test/tests.cpp:26:16: error: ‘oatpp::base::Environment’ has not been declared
   26 |   oatpp::base::Environment::init();
      |                ^~~~~~~~~~~
/home/aboud/sandbox/example-hls-media-stream/test/tests.cpp:33:50: error: ‘oatpp::base::Environment’ has not been declared
   33 |   std::cout << "objectsCount = " << oatpp::base::Environment::getObjectsCount() << "\n";
      |                                                  ^~~~~~~~~~~
/home/aboud/sandbox/example-hls-media-stream/test/tests.cpp:34:52: error: ‘oatpp::base::Environment’ has not been declared
   34 |   std::cout << "objectsCreated = " << oatpp::base::Environment::getObjectsCreated() << "\n\n";
      |                                                    ^~~~~~~~~~~
In file included from /usr/local/include/oatpp-1.4.0/oatpp/oatpp-test/UnitTest.hpp:29,
                 from /home/aboud/sandbox/example-hls-media-stream/test/tests.cpp:2:
/home/aboud/sandbox/example-hls-media-stream/test/tests.cpp:36:29: error: ‘oatpp::base::Environment’ has not been declared
   36 |   OATPP_ASSERT(oatpp::base::Environment::getObjectsCount() == 0);
      |                             ^~~~~~~~~~~
/home/aboud/sandbox/example-hls-media-stream/test/tests.cpp:38:16: error: ‘oatpp::base::Environment’ has not been declared
   38 |   oatpp::base::Environment::destroy();
      |                ^~~~~~~~~~~
make[2]: *** [CMakeFiles/hls-example-test.dir/build.make:76: CMakeFiles/hls-example-test.dir/test/tests.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:139: CMakeFiles/hls-example-test.dir/all] Error 2
make: *** [Makefile:101: all] Error 2

Apparently, the tests.cpp file was not updated to the 1.4.0 version on the commit: afcb50f

With these changes, the build ran successfully.