Update dependency ts-jest to v26.4.1

Author: renovate-bot

package-lock.json

@@ -49,7 +49,7 @@
     "prettier": "2.1.2",
     "subscriptions-transport-ws": "0.9.18",
     "supertest": "5.0.0",
-    "ts-jest": "26.4.0",
+    "ts-jest": "26.4.1",
     "ts-node": "9.0.0",
     "ts-node-dev": "1.0.0-pre.63",
     "typescript": "4.0.3"