rmarkdown 2.31

• Base64 encoded images work with non-HTML output formats now (thanks, @averissimo, #2604).

• Use the argument --syntax-highlighting for Pandoc >= 3.8 since --highlight-style has been deprecated (thanks, @ywwry66, #2602).

• default_output_format() will fall back to html_document if the output format in YAML cannot be recognized.