chore: bump @financial-times/n-express

Bumps the development-dependencies group with 1 update: @financial-times/n-express.


Updates `@financial-times/n-express` from 31.7.0 to 31.8.0

---
updated-dependencies:
- dependency-name: "@financial-times/n-express"
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: development-dependencies
...

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

Author: dependabot[bot]

package-lock.json

@@ -20,7 +20,7 @@
     "@dotcom-reliability-kit/log-error": "^4.1.5"
   },
   "devDependencies": {
-    "@financial-times/n-express": "^31.7.0",
+    "@financial-times/n-express": "^31.8.0",
     "@types/express": "^4.17.21",
     "node-fetch": "^2.7.0"
   }