Implement 'working-directory' argument for action-release

[tyree731]

When running the action-release Github Action, occasionally one might need to perform auto-detection of associated commits in a directory other than the job's working directory, such as in the case where an action performs multiple checkouts. As Github Actions do not, by default, support the ability to run an action in any directory other than the job's working directory, it would be great if action-release could support a working-directory argument for specifying where to detect commit information.

[tyree731]

I put up a possible change which I believe implements the functionality here. I considered adding this to the sentry/cli package itself, but that package already reads in from places such as the environment, and has no builtin notion of the directory to grab releases from, so it seemed fine to chdir from here.

[tyree731]

Pull request implementing this has been merged. Thanks everyone!