Log Message:
latexmk: update to 461.

From v. 4.59 to 4.61
  Add -pdfxelatex and -pdflualatex options to set commands for
    xelatex and lualatex (in analogy with -pdflatex and -latex).
  Correct bug that use of -gg option with -deps-file option
    did not create deps file.
  After run of latex/pdflatex (etc), report count of warnings about missing
    characters (typically unavailable Unicode characters). Messages about
    this may appear only in the .log file and are therefore easily missed
    by the user.
  Fix problem that if biber gets a remote file, latexmk would report it
    incorrectly as a missing file.
  Provide routines for setting all of $latex, etc, with a common pattern.
  Variables, options, placeholders for executing code in *latex before
    inputting source file.  The new variable is $pre_tex_code, the
    options are -pretex, -usepretex, and the new placeholders are %P
    and %U.
  Improved definitions provided for the configuration of latexmk to
    use pythontex; see the file pythontex-latexmkrc in the directory
    example_rcfiles.
  Correction to use of specifications in $clean_ext and
    $clean_full_ext so that %R can appear in the interior of a string
    as in 'pythontex-files-%R/*'.
  Updates of documentation.