pin micromamba to v2.0.5 to fix failing RTD builds

[agriyakhetarpal]

This PR fixes #276. The pin should be temporary.

[agriyakhetarpal]

The prefix is set to /home/docs/checkouts/readthedocs.org/user_builds/jupyterlite-sphinx/conda/jupyterlite-sphinx instead of /tmp/tmp5a5b_ed1/env/envs/jupyterlite-sphinx, which means that the kernels can't be copied.

This does not occur locally, as the prefix shows up as something like /private/var/folders/b3/2bq1m1_50bs4c7305j8vxcqr0000gn/T/tmpgxb2987u/env/envs/jupyterlite-sphinx.

Read the Docs is overriding the prefix somewhere in its build process, which is also the cause for several does not contain any filesystem separator warnings. jupyterlite-xeus looks for the prefix elsewhere, and can't find this overridden one. I guess the fix should be for jupyterlite-xeus to respect the standard conda/mamba environment variables that handle prefixes.

[martinRenou]

Thanks for debugging this! Can you try pinning to micromamba 2.0.5 in the dev env? jupyterlite/xeus#199

I've seen issues with latest micromamba, although I don't have time to debug this so pinning is the way I do for now.

Note that the coming jupyterlite-xeus 4.0.0 release will depend on micromamba directly, and pin it properly.

[agriyakhetarpal]

Thanks, @martinRenou – that works for now!