Add required packages and versions.

Author: mvassilev

README.md

@@ -38,7 +38,7 @@ mamba install`xeus-cpp` notebook -c conda-forge
 Or you can install it from the sources, you will first need to install dependencies
 
 ```bash
-mamba install cmake cxx-compiler xeus-zmq nlohmann_json cppzmq xtl jupyterlab clangdev cpp-argparse -c conda-forge
+mamba install cmake cxx-compiler xeus-zmq nlohmann_json cppzmq xtl jupyterlab clangdev=16 cpp-argparse pugixml -c conda-forge
 ```
 
 Then you can compile the sources (replace `$CONDA_PREFIX` with a custom installation