Move nbformat and nbformat_minor to meta YMap

[davidbrochart]

Tests won't pass because @jupyterlab/shared-models has to be released with the equivalent changes.

cc @hbcarlos

[hbcarlos]

Also, In my opinion, we should change the names of the attributes to match the nbformat specification.

There is only one attribute to change, the nbformatMinor to nbformat_minor

jupyter_ydoc/jupyter_ydoc/ydoc.py

Line 140 in 72f1c7b

self._ystate.set(t, "nbformatMinor", nb["nbformat_minor"])

[davidbrochart]

Good point, fixed in b9c53fa.

[hbcarlos]

Thanks! LGTM.

[davidbrochart]

The CI failure is expected because we need to make the equivalent changes in @jupyterlab/shared-models and release them.