Future-proof against changes to git read-tree --prefix

[rellen]

Is your feature request related to a problem? Please describe.

Recent versions of git will disallow git read-tree --prefix=/ ...
See: https://www.spinics.net/lists/git/msg433678.html
The template will fail if using a recent version of git.
Tested on git version 2.36.0

Already on 'template'
Preparing worktree (detached HEAD 843b4d4)
HEAD is now at 843b4d4 Initial commit
Switched to a new branch 'out'
fatal: Invalid prefix, prefix cannot start with '/'

Describe the solution you'd like

git read-tree --prefix="" ... seems to work for setup.bash changing the below line.
https://github.com/asdf-vm/asdf-plugin-template/blob/main/setup.bash#L170

I am not sure if this is the most robust solution.

Thanks for providing this template!

[jthegedus]

Thanks for the report, makes sense to me. Are you able to create a PR?

[rellen]

@jthegedus PR created :)

[jthegedus]

closed in #54
Thanks @rellen