chore(deps): update dependency @types/koa-mount to v4

Author: renovate-bot

package.json

@@ -51,7 +51,7 @@
     "@types/html-webpack-plugin": "3.2.6",
     "@types/koa": "2.13.4",
     "@types/koa-bodyparser": "5.0.2",
-    "@types/koa-mount": "3.0.1",
+    "@types/koa-mount": "4.0.0",
     "@types/koa-router": "7.4.4",
     "@types/koa-static": "4.0.2",
     "@types/react": "16.14.8",

yarn.lock

@@ -990,10 +990,10 @@
   resolved "https://registry.yarnpkg.com/@types/koa-compose/-/koa-compose-3.2.2.tgz#dc106e000bbf92a3ac900f756df47344887ee847"
   integrity sha1-3BBuAAu/kqOskA91bfRzRIh+6Ec=
 
-"@types/koa-mount@3.0.1":
-  version "3.0.1"
-  resolved "https://registry.yarnpkg.com/@types/koa-mount/-/koa-mount-3.0.1.tgz#2c068d1696b173c62c316158210c4316c4401f57"
-  integrity sha512-SkAE5yjrbJCeRoeU2mxQsopskcIMksQ4GXIHEaK87XRUHDESLtUpsfOdiCQOtYGiNXVljR/LzWYBq+r6BIW/dw==
+"@types/koa-mount@4.0.0":
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/@types/koa-mount/-/koa-mount-4.0.0.tgz#aa0505763c0d20bf4a16cdec0d9ccd2f4f2d2a86"
+  integrity sha512-56iBULArwY3uKLl28eRFchZ2v0diEoJzJbDaHH/ehgruF/s2/KMHyWsKcIhvDJ3tGdKu9oZNQvxaMg++1IKFdA==
   dependencies:
     "@types/koa" "*"