Update dependency @types/jest to v26

Author: renovate-bot

package.json

@@ -55,7 +55,7 @@
   "devDependencies": {
     "@types/co-body": "0.0.3",
     "@types/ioredis": "^4.14.6",
-    "@types/jest": "^24.0.18",
+    "@types/jest": "26.0.23",
     "@types/koa": "^2.11.2",
     "@types/koa-router": "^7.4.0",
     "@types/lodash": "^4.14.138",