[GHA] install vdt for ROOT

.github/workflows/build-test.yml

@@ -270,7 +270,10 @@ jobs:
              tar -xzvf "$ROOT_file"
              rm "$ROOT_file"
              source root/bin/thisroot.sh
-             cat root/cmake/ROOTConfig.cmake
+             # Need to manually install vdt
+             git clone https://github.com/drbenmorgan/vdt.git
+             cmake -DCMAKE_INSTALL_PREFIX="$ROOTSYS" -S vdt -B vdtbuild
+             cmake --build vdtbuild --target install --config Release
           fi
 
           # we'll install some dependencies with shared libraries, so need to let the OS know