Fix `binder.org` (via `thebe`) integration

[michaelweinold]

The interactive code execution on binder.org servers enabled by the Thebe service is currently timing out. This is likely related to the environment set up in jupyter-book-binder-environment.

[michaelweinold]

jupyter-lite integration seems to have arrived:

• [ ] https://github.com/executablebooks/thebe/issues/412

[michaelweinold]

"Running thebe on a local server":

• [ ] https://github.com/ouseful-testing/jupyter-book-server-proxy/issues/2
• [ ] https://github.com/executablebooks/sphinx-thebe/issues/27

[michaelweinold]

...binder.org will not be the way to go. Loading a Binder instance takes time (especially, if Brightway needs to be installed every time). Instead, local execution (WASM) will enable scalability. Compare: https://github.com/brightway-lca/brightway-interactive/issues/19