binder not working

[JessicaS11]

Describe the bug
The binder environment does not appear to be building. After repeated attempts, it fails while stuck on "Using CondaBuildPack builder".

[PennyHow]

I also experienced this. For me, it seems that the binder build cannot solve the conda environment for installation of the polartoolkits package.

[mdtanker]

Thanks for checking this. I've tried a few things to fix this, but haven't found a reliable method. For now, until (if) I'm able to reduce PolarToolkit's heavy dependencies, I have moved the Binder environment to a separate repository, so that it is not rebuild with every new commit to the main repo.

I've used nbgitpuller to create a link which will use the above repo for the build, but the main repo for the content. Below is the badge with this link:

Unfortunately, the sphinx-book-theme I use for the documentation doesn't allow altering the Binder url, so I've had to disable the launch-binder button for all the gallery and user guide examples. Users will just have to navigate to the ipynb from the main Binder site. This issue should track when we can add back the launch-binder buttons.

This issue should close with #195