Bump ts-jest from 26.4.4 to 26.5.6

Bumps [ts-jest](https://github.com/kulshekhar/ts-jest) from 26.4.4 to 26.5.6.
- [Release notes](https://github.com/kulshekhar/ts-jest/releases)
- [Changelog](https://github.com/kulshekhar/ts-jest/blob/master/CHANGELOG.md)
- [Commits](kulshekhar/ts-jest@v26.4.4...v26.5.6)

---
updated-dependencies:
- dependency-name: ts-jest
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]