Bump ts-jest from 26.3.0 to 26.4.0

Bumps [ts-jest](https://github.com/kulshekhar/ts-jest) from 26.3.0 to 26.4.0.
- [Release notes](https://github.com/kulshekhar/ts-jest/releases)
- [Changelog](https://github.com/kulshekhar/ts-jest/blob/master/CHANGELOG.md)
- [Commits](https://github.com/kulshekhar/ts-jest/compare/v26.3.0...v26.4.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -31,7 +31,7 @@
     "jest-junit": "^11.1.0",
     "request": "^2.88.2",
     "requestretry": "^4.1.1",
-    "ts-jest": "^26.3.0",
+    "ts-jest": "^26.4.0",
     "typescript": "^4.0.3",
     "yarn": "^1.22.5"
   },