Update dependency ts-jest to v26.5.6

Author: renovate-bot

package-lock.json

@@ -49,7 +49,7 @@
     "prettier": "2.2.1",
     "subscriptions-transport-ws": "0.9.18",
     "supertest": "6.1.3",
-    "ts-jest": "26.5.5",
+    "ts-jest": "26.5.6",
     "ts-node": "9.1.1",
     "ts-node-dev": "1.1.6",
     "typescript": "4.2.4"