Bump govuk_app_config from 9.14.6 to 9.15.0

Bumps [govuk_app_config](https://github.com/alphagov/govuk_app_config) from 9.14.6 to 9.15.0.
- [Changelog](https://github.com/alphagov/govuk_app_config/blob/main/CHANGELOG.md)
- [Commits](alphagov/govuk_app_config@v9.14.6...v9.15.0)

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

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

Gemfile.lock

@@ -126,7 +126,7 @@ GEM
       multi_json (~> 1.11)
       os (>= 0.9, < 2.0)
       signet (>= 0.16, < 2.a)
-    govuk_app_config (9.14.6)
+    govuk_app_config (9.15.0)
       logstasher (~> 2.1)
       opentelemetry-exporter-otlp (>= 0.25, < 0.30)
       opentelemetry-instrumentation-all (>= 0.39.1, < 0.69.0)
@@ -546,7 +546,7 @@ GEM
     unicode-display_width (2.5.0)
     uri (0.13.1)
     useragent (0.16.10)
-    webrick (1.8.2)
+    webrick (1.9.0)
     websocket (1.2.11)
     xpath (3.2.0)
       nokogiri (~> 1.8)