Bump ts-jest from 26.5.4 to 26.5.6 (#39)

Author: dependabot[bot]

package-lock.json

@@ -21,7 +21,7 @@
     "eslint-plugin-prettier": "^3.3.1",
     "jest": "^26.6.3",
     "prettier": "^2.2.1",
-    "ts-jest": "^26.5.4"
+    "ts-jest": "^26.5.6"
   },
   "dependencies": {
     "@octokit/auth-app": "^3.3.0",