Remove libxmljs dependency

package.json

@@ -34,16 +34,12 @@
     "seedrandom": "^3.0.1",
     "yaml": "^1.6.0"
   },
-  "optionalDependencies": {
-    "libxmljs": "^0.19.5"
-  },
   "devDependencies": {
     "@types/jsonwebtoken": "^8.3.2",
     "@types/koa": "^2.0.49",
     "@types/koa-compress": "^2.0.9",
     "@types/koa-router": "^7.0.42",
     "@types/koa-static": "^4.0.1",
-    "@types/libxmljs": "^0.18.3",
     "@types/mithril": "^2.0.0",
     "@types/mongodb": "^3.1.31",
     "@types/parsimmon": "^1.10.0",