chore(deps-dev): bump vitepress from 0.20.10 to 0.21.3 (#615)

Author: dependabot[bot]

package-lock.json

@@ -96,7 +96,7 @@
     "lodash": "^4.17.20",
     "ts-node": "^10.0.0",
     "typescript": "^4.0.5",
-    "vitepress": "^0.20.0",
+    "vitepress": "^0.21.3",
     "vue": "^3.0.2",
     "vue2": "npm:vue@2"
   },