Bump pkg-config from 1.3.5 to 1.3.6 (mastodon#10235)

Bumps [pkg-config](https://github.com/ruby-gnome2/pkg-config) from 1.3.5 to 1.3.6.
- [Release notes](https://github.com/ruby-gnome2/pkg-config/releases)
- [Changelog](https://github.com/ruby-gnome2/pkg-config/blob/master/NEWS)
- [Commits](ruby-gnome/pkg-config@1.3.5...1.3.6)

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

Gemfile.lock

@@ -400,7 +400,7 @@ GEM
     pg (1.1.4)
     pghero (2.2.0)
       activerecord
-    pkg-config (1.3.5)
+    pkg-config (1.3.6)
     powerpack (0.1.2)
     premailer (1.11.1)
       addressable