Election for Takashi Katou as Committer on Eclipse Sprotty

Takashi recently started contributing to the Eclipse Sprotty team and has already made an impact on the project.

Here's a list of pull requests:
- https://github.com/eclipse/sprotty/pulls?q=is%3Apr+author%3Atohosaku+

These contributions are particularly valuable for the code quality of the project, see e.g. #227.

For these reasons and the long-term outlook for their involvement on the
team, it is my pleasure to nominate Takashi as a committer on Eclipse Sprotty.