Bumps [pkg-config](https://github.com/ruby-gnome/pkg-config) from 1.3.9 to 1.4.0.
- [Release notes](https://github.com/ruby-gnome/pkg-config/releases)
- [Changelog](https://github.com/ruby-gnome/pkg-config/blob/master/NEWS)
- [Commits](https://github.com/ruby-gnome/pkg-config/compare/1.3.9...1.4.0

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>