See discussion at <https://gitlab.com/nonguix/nonguix/-/merge_requests/346>.
Default geiser-guile-binary is guile, which uses an old guix. This leads to
annoying errors when trying to work with the this repository from geiser. So,
set the variable to '("guix" "repl"), which will use the current guix command,
making everything work properly. Note that this may be unexpected for someone
working with a local Guix checkout (differing Guix version) and may need
adjusting then.
* .dir-locals.el (scheme-mode): Add geiser-guile-binary setting.
Signed-off-by: John Kehayias <john.kehayias@protonmail.com>