allow to use bun as a package manager in the force option

[wcastand]

Note that Gluegun is community-supported and the core team will not be adding new features other than those submitted as PRs by the community.

Is your feature request related to a problem? Please describe.
was trying to add bun support to react-native-ci-cli and realized gluegun doesn't accept bun as a value for package manager in the force property.

Describe the solution you'd like
Support bun as a package manager, so i can use it in the force option.

Describe alternatives you've considered
Not sure there is any unfortunately, except not support bun on the cli.