fix: remarkjs link

Direct link to github sources because remarkjs.com is not available today.

Correct error The resource from “https://raw.githubusercontent.com/gnab/remark/gh-pages/downloads/remark-0.15.0.min.js” was blocked due to MIME type (“text/plain”) mismatch (X-Content-Type-Options: nosniff).

Formation_airGRiwrm.Rmd

@@ -7,7 +7,7 @@ date: "Montpellier / Clisson, le 6 juillet 2023 (MAJ `r format(Sys.time(), '%d/%
 output:
   xaringan::moon_reader:
     lib_dir: libs
-    chakra: https://github.com/gnab/remark/raw/gh-pages/downloads/remark-0.15.0.min.js
+    chakra: https://cdn.jsdelivr.net/gh/gnab/remark@gh-pages/downloads/remark-0.15.0.min.js
     css: ["styles/remark_inrae.css", "styles/fonts_inrae.css", "styles/custom.css"]
     nature:
       highlightStyle: github