Add dependency to texlive-lang-french to the base image

[alainbret]

Hi,

I have a problem when generating a pdf report with the 'lang: fr-FR' parameter in the Rmarkdown report from my shiny app.
It works with HTML and Word, but not with PDF.

On local site, it works perfectly with all formats.

Beginning of the report.Rmd file:

---

title:    "Salle de Musculation de l'Aviron Bayonnais"
...
...

lang: fr-FR

---


Error in log file:

/opt/connect/ext/pandoc/2.11/pandoc +RTS -K512m -RTS report.knit.md --to latex --from markdown+autolink_bare_uris+tex_math_single_backslash --output report.tex --lua-filter /opt/R/4.1.1/lib/R/library/rmarkdown/rmarkdown/lua/pagebreak.lua --lua-filter /opt/R/4.1.1/lib/R/library/rmarkdown/rmarkdown/lua/latex-div.lua --self-contained --table-of-contents --toc-depth 2 --number-sections --highlight-style tango --pdf-engine pdflatex --variable graphics 

2021-11-02T22:13:14.006150+00:00 shinyapps[5008281]: ! Package babel Error: Unknown option `french'. Either you misspelled it

Regards,
Alain