Allow `asdf-vm/actions/install` (to pass) without `.tool-versions` file

Why does this action fail is there isn't any `.tool-versions` file?
That's' not how `asdf install` behaves on my local computer.
There it falls back to check in my home directory for `~/.tool-versions` (which this action doesn't seem to do?).
And even then if it isn't there, it doesn't fail, right?

I'd like to use this for a reusable workflow in my organization, where we can "install things from asdf if the repository is using a `.tool-versions` file, otherwise not".

Today, running this action without a `.tool-versions` file in the current directory, the action fails with:
`Action failed with error Error: ENOENT: no such file or directory, open '.tool-versions'`

Start by tracing where the action reads `.tool-versions` and how its install entry point handles a missing file. Compare that behavior with the expected fallback described in the issue; done means a workflow without a repository `.tool-versions` file completes successfully while repositories that use one still install their declared tools.

Written by the indexing model from the issue text.