Update dependency @types/jest to v26.0.20

Author: renovate-bot

package-lock.json

@@ -34,7 +34,7 @@
     "jest-diff": ">=23.0"
   },
   "devDependencies": {
-    "@types/jest": "26.0.15",
+    "@types/jest": "26.0.20",
     "@vue/test-utils": "1.1.1",
     "babel-core": "7.0.0-bridge.0",
     "jest": "26.6.3",