Update gstreamer-editing-services to version 1.18.5 / rev 38 via SR 947912
    
    https://build.opensuse.org/request/show/947912
    by user iznogood + dimstar_suse
    - Fix parameters passed to meson: gtk_doc should be doc. Meson 0.60
      became strict and no longer accepts invalid parameters.
    - Drop hotdoc BuildRequires: as we pass -Ddoc=disabled to meson,
      this dependency is not needed.