maint: add pre-commit config

[consideRatio]

I've now activated pre-commit.ci at https://github.com/organizations/jupyterhub/settings/installations/17782968.

[github-actions[bot]]

:point_left: Launch a binder notebook on this branch for commit f71a58ba05b6fa66b121d7c398c9b9a0349eb042

[github-actions[bot]]

:point_left: Launch a binder notebook on this branch for commit b1af2e99596d6e5a2b53ea07b736697a06f34e59

[yuvipanda]

Thanks for working on this!

We should make sure that the tigervnc package that we vendor does not formatting applied to it, as that would make re-vendoring it difficult. The 'right' thing to do is to spin it out into its own package, but I don't know if any of us have the bandwidth for that right now.

[github-actions[bot]]

:point_left: Launch a binder notebook on this branch for commit b1af2e99596d6e5a2b53ea07b736697a06f34e59

[github-actions[bot]]

:point_left: Launch a binder notebook on this branch for commit 9e3daca12bd4e503b7f5c8bedb33b382282a5db4

[github-actions[bot]]

:point_left: Launch a binder notebook on this branch for commit 9aced4cb6026e63681b23c86d3773e9ed359f4fb