fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-PATHTOREGEXP-7925106

package.json

@@ -11,7 +11,7 @@
     "Nick Baugh <[email protected]> (http://niftylettuce.com/)"
   ],
   "dependencies": {
-    "@koa/router": "^12.0.1",
+    "@koa/router": "^13.0.1",
     "@ladjs/i18n": "^8.0.3",
     "@ladjs/koa-better-static": "^2.0.1",
     "@ladjs/koa-cache-responses": "^0.0.3",