Update fakefs requirement from ~> 0.19.2 to ~> 0.20.0
Update fakefs requirement from ~> 0.19.2 to ~> 0.20.0

Updates the requirements on [fakefs](https://github.com/fakefs/fakefs) to permit the latest version.
- [Release notes](https://github.com/fakefs/fakefs/releases)
- [Commits](https://github.com/fakefs/fakefs/compare/v0.19.2...v0.20.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
pivotal/LicenseFinder,pivotal/LicenseFinder,pivotal/LicenseFinder,pivotal/LicenseFinder,pivotal/LicenseFinder,pivotal/LicenseFinder,pivotal/LicenseFinder