Update dependency @types/jest to v26

Author: renovate-bot

frontend/package-lock.json

@@ -22,7 +22,7 @@
     "vuex": "4.0.0"
   },
   "devDependencies": {
-    "@types/jest": "24.9.1",
+    "@types/jest": "26.0.22",
     "@typescript-eslint/eslint-plugin": "4.22.0",
     "@typescript-eslint/parser": "4.22.0",
     "@vue/cli-plugin-babel": "4.5.12",