Update doxygen to version 1.9.6 / rev 91 via SR 1072283
    
    https://build.opensuse.org/request/show/1072283
    by user pgajdos + dimstar_suse
    - Fix boundingbox parsing of graphviz PDFs when using cairo >=
      1.17.6, add:
      * Fix-boundingbox-parsing_part1.patch
      * Fix-boundingbox-parsing_part2.patch
      * Fix-boundingbox-parsing_part3.patch
      * Fix-boundingbox-parsing_part4.patch (forwarded request 1072216 from StefanBruens)