`license_finder` does not load `jh/Gemfile` properly

Problem to solve

license_finder does not load jh/Gemfile properly: https://gitlab.com/gitlab-jh/gitlab/-/jobs/1560768053

References

• gitlab-org/gitlab#340052
• https://github.com/pivotal/LicenseFinder/issues/605
• https://github.com/pivotal/LicenseFinder/issues/838

/cc @kwiebers