bump celltags to 1.0.0

[jasongrout]

Cell tags was merged into core in #7407. We decided around the 1.0 release that anything in core should be at least 1.0.0 so that we could release patch versions of those libraries with patch versions of jlab. Hence, I think we should bump the version of celltags to at least 1.0.0.

[telamonian]

Would it make sense to bump celltags straight to 2.0.0? The more in lockstep all of the package versions are, the easier it is to get the versions right when defining dependencies in a package.json. For example, when writing an extension that targets a particular version of jlab core, I often find it pretty confusing to remember the special versioning rules for @jupyterlab/coreutils and @jupyterlab/services.

[jasongrout]

I'm okay with either one. Note that the minor versions are already off in general, and certainly patch numbers can be off.

[telamonian]

I'll put a PR for this on my todo list