LaTeX Error: File figure-latex unnamed-chunk not found.
On the CI, cache is referencing files located in the *_file
sub folder of the Rmd wich is not saved with the cache.
At each new job, as the file is not changed, the cache is not regenerated and the latex figure stored next to the Rmd is missing.
Ref: https://stackoverflow.com/questions/13479641/knitr-latex-error-file-figure-unnamed-chunk-1-not-found