use @lumino instead of @phospor

[nimo23]

Currently, theia uses and builds upon https://github.com/phosphorjs/phosphor. But this project is not more maintained. Please consider to switch to https://github.com/jupyterlab/lumino (which is the successor of phosphor) to make use of those improvements. The lumino project is actively maintained as it is used for JupyterLab. It has many improvements in compare to phosphor and it will likely improve the overall theia workspace, too.

[nimo23]

There is already a discussion about this in #6501. So I will close this for now.