Bump version to 0.6.0

[echarles]

Bump version to 0.6.0 to prepare the next release.

[juhasch]

Thank you for the PR!

[echarles]

Thx @juhasch 🙏

I let you further cut the release. Please ping me for anything.

[juhasch]

@echarles your help very much appreciated.
I guess I will do a 0.6.1 due to PR #144 and will upload it to PyPi then. I also need write permissions on conda-forge to update the feedstock, as I don't have them right now.

[echarles]

I also need write permissions on conda-forge to update the feedstock, as I don't have them right now.

@bollwyvl may help for this.

[bollwyvl]

With any luck, the bot should pick it up in a few hours... Anybody can make a PR, though!

[juhasch]

Hi @bollwyvl
can you help me check what is going on the two repos:

1. https://github.com/conda-forge/jupyter_contrib_core-feedstock
   Does not seem to create a PR automatically. Not sure how to trigger it.
2. https://github.com/conda-forge/jupyter_nbextensions_configurator-feedstock
   There is a PR, but the assigned reviewers did not review it. I have no permissions to do so.