Bump govuk_app_config from 2.2.1 to 2.2.2

Bumps [govuk_app_config](https://github.com/alphagov/govuk_app_config) from 2.2.1 to 2.2.2.
- [Release notes](https://github.com/alphagov/govuk_app_config/releases)
- [Changelog](https://github.com/alphagov/govuk_app_config/blob/master/CHANGELOG.md)
- [Commits](alphagov/govuk_app_config@v2.2.1...v2.2.2)

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -110,11 +110,11 @@ GEM
     globalid (0.4.2)
       activesupport (>= 4.2.0)
     govuk_ab_testing (2.4.2)
-    govuk_app_config (2.2.1)
+    govuk_app_config (2.2.2)
       logstasher (>= 1.2.2, < 1.4.0)
       sentry-raven (>= 2.7.1, < 3.1.0)
       statsd-ruby (~> 1.4.0)
-      unicorn (>= 5.4, < 5.6)
+      unicorn (>= 5.4, < 5.7)
     govuk_publishing_components (21.63.3)
       govuk_app_config
       kramdown
@@ -335,7 +335,7 @@ GEM
       unf_ext
     unf_ext (0.0.7.7)
     unicode-display_width (1.7.0)
-    unicorn (5.5.5)
+    unicorn (5.6.0)
       kgio (~> 2.6)
       raindrops (~> 0.7)
     webdrivers (4.4.1)