Bump flat-cache from 3.2.0 to 4.0.0

Bumps [flat-cache](https://github.com/jaredwray/flat-cache) from 3.2.0 to 4.0.0.
- [Release notes](https://github.com/jaredwray/flat-cache/releases)
- [Changelog](https://github.com/jaredwray/flat-cache/blob/master/changelog.md)
- [Commits](https://github.com/jaredwray/flat-cache/compare/v3.2.0...v4.0.0)

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

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

package.json

@@ -42,7 +42,7 @@
     "discord.js": "^13.16.0",
     "fast-json-stable-stringify": "^2.1.0",
     "fastify": "^4.23.0",
-    "flat-cache": "^3.0.4",
+    "flat-cache": "^4.0.0",
     "form-data": "^4.0.0",
     "geo-tz": "^7.0.7",
     "handlebars": "^4.7.7",