Bump govuk_app_config from 2.8.3 to 3.0.0

Bumps [govuk_app_config](https://github.com/alphagov/govuk_app_config) from 2.8.3 to 3.0.0.
- [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@v2.8.3...v3.0.0)

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

Gemfile.lock

@@ -24,19 +24,23 @@ GEM
     docile (1.3.5)
     dotenv (2.7.6)
     erubis (2.7.0)
-    faraday (1.3.0)
+    faraday (1.4.1)
+      faraday-excon (~> 1.1)
       faraday-net_http (~> 1.0)
+      faraday-net_http_persistent (~> 1.1)
       multipart-post (>= 1.2, < 3)
-      ruby2_keywords
+      ruby2_keywords (>= 0.0.4)
+    faraday-excon (1.1.0)
     faraday-net_http (1.0.1)
+    faraday-net_http_persistent (1.1.0)
     ffi (1.14.2)
     foreman (0.87.2)
-    govuk_app_config (2.8.3)
+    govuk_app_config (3.0.0)
       logstasher (>= 1.2.2, < 2.2.0)
       sentry-raven (~> 3.1.1)
       statsd-ruby (~> 1.5.0)
       unicorn (>= 5.4, < 5.9)
-    i18n (1.8.9)
+    i18n (1.8.10)
       concurrent-ruby (~> 1.0)
     kgio (2.11.3)
     listen (1.3.1)
@@ -130,8 +134,8 @@ GEM
     rubocop-rspec (1.42.0)
       rubocop (>= 0.87.0)
     ruby-progressbar (1.11.0)
-    ruby2_keywords (0.0.2)
-    sentry-raven (3.1.1)
+    ruby2_keywords (0.0.4)
+    sentry-raven (3.1.2)
       faraday (>= 1.0)
     sidekiq (6.1.2)
       connection_pool (>= 2.2.2)