bug#42385: guile-based jupyter kernels mix guile3 and guile2.2

[Jesse Gibbons]

jupyter-guile-kernel and guix-jupyter mix guile3 and guile2.2.

- jupyter-guile-kernel only has one of its dependencies in 
GUILE_LOAD_PATH, so it doesn't build.

- guix-jupyter builds successfully, but searches in the wrong directory 
for guix-jupyter-kernel.scm.

jupyter-guile-kernel requires guile-json1 which has not been packaged 
for guile3, and is still built with guile2.2. IINM the 
jupyter-guile-kernel repository has been updated to build with guile3, 
so it might be worth updating. Unfortunately, there are no releases in 
its github repository. I expect guix-jupyter will be much easier to fix.