chore(deps): update dependency @types/chai to v4.1.7

Author: renovate-bot

package-lock.json

@@ -67,7 +67,7 @@
     "@sourcegraph/prettierrc": "^2.2.0",
     "@sourcegraph/tsconfig": "^3.0.0",
     "@sourcegraph/tslint-config": "^12.0.0",
-    "@types/chai": "4.1.6",
+    "@types/chai": "4.1.7",
     "@types/chai-as-promised": "7.1.0",
     "@types/glob": "7.1.1",
     "@types/lodash": "4.14.116",