Allow binderbot to build notebooks not in the base path

[salvis2]

I haven't been able to build notebooks that are not in the root directory of the gallery repository. I see in the GitHub Action that comes with the example gallery repo has the following line:

git rm --cached -r .

This appears to remove all files that are in subdirectories, but nothing in the root directory. As a consequence, trying to edit the GitHub Action to look at notebooks in a subdirectory such as examples/ returns status code 500.

I can remove this line, add in a git add examples/ and confirm that the notebooks are present, but I still get errors trying to interact with them in Binder:

Uploading examples/ICESat-2_DAAC_DataAccess2_Subsetting.ipynb...❌ error running examples/ICESat-2_DAAC_DataAccess2_Subsetting.ipynb: 500, message='Internal Server Error', url=URL('https://hub.gke.mybinder.org/user/salvis2-icepyx-n5s2nyw9/api/contents/examples/ICESat-2_DAAC_DataAccess2_Subsetting.ipynb')

If anyone has ideas about how to enable this, I'm willing to work on it. I also would love some pointers on what the code is doing / what API it is calling / etc. I'm digging through the binderbot code to learn a bit.