meson.build: fix pkg-config generation
The code was previously using glib_dep.version() as a version for gio which generates an invalid version like "gio-2.0 2.59.1" in the pkg-config file.
The code was previously using glib_dep.version() as a version for gio which generates an invalid version like "gio-2.0 2.59.1" in the pkg-config file.