tfversion list --installed produces an error on clean installation.

[mmourick]

Description

Upon clean installation tfversion produces an error when listing installed terraform versions.
I would expect tfversion to display an empty list instead.

Reference

> tfversion list --installed

error listing installation directory: open /Users/mathijs/.tfversion: no such file or directory%

[ChrisTerBeke]

Seems like we need to ensure this directory before running the list --installed command.

[mmourick]

@ChrisTerBeke Submitted a PR that does exactly that, ensuring the directory exists does indeed fix the issue.