Bump govuk_app_config from 8.1.1 to 9.0.4

Bumps [govuk_app_config](https://github.com/alphagov/govuk_app_config) from 8.1.1 to 9.0.4.
- [Changelog](https://github.com/alphagov/govuk_app_config/blob/main/CHANGELOG.md)
- [Commits](alphagov/govuk_app_config@v8.1.1...v9.0.4)

---
updated-dependencies:
- dependency-name: govuk_app_config
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Gemfile.lock

@@ -137,7 +137,7 @@ GEM
     googleapis-common-protos-types (1.7.0)
       google-protobuf (~> 3.14)
     govuk_ab_testing (2.4.3)
-    govuk_app_config (8.1.1)
+    govuk_app_config (9.0.4)
       logstasher (~> 2.1)
       opentelemetry-exporter-otlp (~> 0.25.0)
       opentelemetry-instrumentation-all (~> 0.39.1)