cloudfoundry-cli 6.1.0

This change updates the formula to install cloudfoundry-cli v6.1.0. It
also updates the formula to handle the new Version and BuiltOnDate
constants.
cloudfoundry-cli: add 6.1.0 bottle.

Closes #28319.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>