rmarkdown 2.26

• rmarkdown now requires knitr >= 1.43.

• Get rid of the superfluous warning in find_pandoc() (thanks, @jszhao, #2527).

• Removed the stringr dependency since it is used only once in the package and the equivalent base R code is simple enough (thanks, @etiennebacher, #2530).

• For the output format option fig_crop: auto, it will now use the same logic as in knitr to decide if cropping is possible (yihui/knitr#2246).

• Avoid corrupting input files by accident (thanks, @J-Moravec, #2534).