chore(package): update @types/chai to version 4.0.0 (#270)

Closes #154

Author: felixfbecker

package.json

@@ -53,7 +53,7 @@
     "vscode-languageserver-types": "^3.0.3"
   },
   "devDependencies": {
-    "@types/chai": "3.4.35",
+    "@types/chai": "4.0.0",
     "@types/chai-as-promised": "0.0.31",
     "@types/chalk": "0.4.31",
     "@types/glob": "5.0.30",