build(deps-dev): bump @intlify/unplugin-vue-i18n in /webapp

Bumps [@intlify/unplugin-vue-i18n](https://github.com/intlify/bundle-tools/tree/HEAD/packages/unplugin-vue-i18n) from 5.2.0 to 6.0.3.
- [Release notes](https://github.com/intlify/bundle-tools/releases)
- [Changelog](https://github.com/intlify/bundle-tools/blob/main/packages/unplugin-vue-i18n/CHANGELOG.md)
- [Commits](https://github.com/intlify/bundle-tools/commits/unplugin-vue-i18n@6.0.3/packages/unplugin-vue-i18n)

---
updated-dependencies:
- dependency-name: "@intlify/unplugin-vue-i18n"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

webapp/package.json

@@ -24,7 +24,7 @@
     "vue-router": "^4.4.5"
   },
   "devDependencies": {
-    "@intlify/unplugin-vue-i18n": "^5.2.0",
+    "@intlify/unplugin-vue-i18n": "^6.0.3",
     "@tsconfig/node22": "^22.0.0",
     "@types/bootstrap": "^5.2.10",
     "@types/node": "^22.9.0",