Bump sequelize-typescript from 2.1.3 to 2.1.5 (#522)

Bumps [sequelize-typescript](https://github.com/RobinBuschmann/sequelize-typescript) from 2.1.3 to 2.1.5.
- [Release notes](https://github.com/RobinBuschmann/sequelize-typescript/releases)
- [Changelog](https://github.com/sequelize/sequelize-typescript/blob/master/CHANGELOG.md)
- [Commits](sequelize/sequelize-typescript@v2.1.3...v2.1.5)

---
updated-dependencies:
- dependency-name: sequelize-typescript
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>