security/p11-kit: unbreak build with Meson 0.61.0

doc/manual/meson.build:69:8: ERROR: gnome.gtkdoc keyword argument 'dependencies' was of type array[CustomTarget | PkgConfigDependency] but should have been array[Dependency | SharedLibrary | StaticLibrary]

PR: 260943
Reported by: antoine (via exp-run)
Regressed by: https://github.com/mesonbuild/meson/commit/566c2c9a9c98