Avoid "Scheme implementation" prompt on export

[Roi Martin <jroi.martin@gmail.com>]

Hello,

I have an org document with the following structure:

---
Racket code block:

#+begin_src scheme
  #lang racket
  (+ 1 2)
#+end_src

Chez Scheme code block:

#+begin_src scheme
  (+ 3 4)
#+end_src
---

It includes several code blocks with different scheme implementations
(e.g. Racket and Chez).

When I export the document to HTML, both from the Org Export Dispatcher
(C-c C-e) or calling (org-publish-all), I'm asked to choose a "Scheme
implementation" for every code block.

If I understand correctly, I can set a default Scheme implementation
with the `geiser-scheme-implementation' variable.  However, I would like
to specify an implementation per block without having to answer the
prompt every time.

Is it possible?

Just in case, it is useful, I'm using the following package versions:

- GNU Emacs 29.4
- org 9.6.15
- geiser 20240907.2235
- geiser-chez 20230707.1334
- geiser-guile 20240920.35
- geiser-racket 20210421.125
- htmlize 20240915.1657

Thanks for your help!

Best,
        Roi