Update dependency @types/chai to v4.2.21

Author: renovate[bot]

package-lock.json

@@ -87,7 +87,7 @@
     "@babel/preset-env": "7.14.7",
     "@babel/preset-typescript": "7.14.5",
     "@babel/register": "7.14.5",
-    "@types/chai": "^4.2.19",
+    "@types/chai": "4.2.21",
     "@types/chai-as-promised": "^7.1.4",
     "@types/chai-subset": "^1.3.3",
     "@types/debug": "^4.1.5",