Bump pkg-config from 1.4.7 to 1.4.9 (#18916)

Bumps [pkg-config](https://github.com/ruby-gnome/pkg-config) from 1.4.7 to 1.4.9.
- [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/1.4.7...1.4.9)

---
updated-dependencies:
- dependency-name: pkg-config
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -450,7 +450,7 @@ GEM
     pg (1.4.2)
     pghero (2.8.3)
       activerecord (>= 5)
-    pkg-config (1.4.7)
+    pkg-config (1.4.9)
     posix-spawn (0.3.15)
     premailer (1.14.2)
       addressable