Use rnc2rng
I had to update the rn[cg] files recently. Historically we used trang [1] which is a java program. As I have a new laptop, I did not have trang installed and I was tired by the number of dependencies needed. So I found rnc2rng [2] which is written in Python and so limit the requirements.
Unfortunately, the generated rng is not strictly the same, so I propose to make one conversion commit.
[1] https://github.com/relaxng/jing-trang
[2] https://pypi.org/project/rnc2rng/