Bump govuk_app_config from 9.15.6 to 9.15.7

Bumps [govuk_app_config](https://github.com/alphagov/govuk_app_config) from 9.15.6 to 9.15.7.
- [Changelog](https://github.com/alphagov/govuk_app_config/blob/main/CHANGELOG.md)
- [Commits](alphagov/govuk_app_config@v9.15.6...v9.15.7)

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

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

Gemfile.lock

@@ -203,7 +203,7 @@ GEM
       rinku (~> 2.0)
       sanitize (~> 6)
     govuk_ab_testing (3.0.0)
-    govuk_app_config (9.15.6)
+    govuk_app_config (9.15.7)
       logstasher (~> 2.1)
       opentelemetry-exporter-otlp (>= 0.25, < 0.30)
       opentelemetry-instrumentation-all (>= 0.39.1, < 0.71.0)
@@ -284,7 +284,7 @@ GEM
     logstasher (2.1.5)
       activesupport (>= 5.2)
       request_store
-    loofah (2.23.1)
+    loofah (2.24.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)
     mail (2.8.1)