Fix build on Debian Bullseye
bibtex_fudge must be set for latexmk 4.70a (included in Debian Bullseye) to workaround output directory restrictions in bibtex. see also https://tex.stackexchange.com/a/564691
bibtex_fudge must be set for latexmk 4.70a (included in Debian Bullseye) to workaround output directory restrictions in bibtex. see also https://tex.stackexchange.com/a/564691