build: remove a header defined twice
Fixes the following warning:
src/libnm-client-impl/meson.build:139: WARNING: Keyword argument "header" defined multiple times. WARNING: This will be an error in future Meson releases.
Fixes the following warning:
src/libnm-client-impl/meson.build:139: WARNING: Keyword argument "header" defined multiple times. WARNING: This will be an error in future Meson releases.