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] <[email protected]>

Gemfile.lock

@@ -167,7 +167,7 @@ GEM
       rake (>= 13)
     googleapis-common-protos-types (1.16.0)
       google-protobuf (>= 3.18, < 5.a)
-    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)
@@ -213,7 +213,7 @@ 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)
@@ -247,14 +247,14 @@ GEM
       net-protocol
     netrc (0.11.0)
     nio4r (2.7.4)
-    nokogiri (1.17.2)
+    nokogiri (1.18.1)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
-    nokogiri (1.17.2-aarch64-linux)
+    nokogiri (1.18.1-aarch64-linux-gnu)
       racc (~> 1.4)
-    nokogiri (1.17.2-arm64-darwin)
+    nokogiri (1.18.1-arm64-darwin)
       racc (~> 1.4)
-    nokogiri (1.17.2-x86_64-linux)
+    nokogiri (1.18.1-x86_64-linux-gnu)
       racc (~> 1.4)
     null_logger (0.0.1)
     oauth2 (2.0.9)