{cache-dir}/virtualenvs may be too volatile a storage location for some users

• I have searched the issues of this repo and believe that this is not a duplicate.
• I have searched the documentation and believe that my question is not covered.

Feature Request

Poetry by default saves its virtualenvs in {cache-dir}/virtualenvs which by default is ~/.cache/pypoetry/virtualenvs (Linux) and ~/Library/Caches/pypoetry/virtualenvs (MacOS). However, these folders are generally considered to be safe to be removed: Linux, MacOS

XDG also specifies to use the cache directory for non essential files. (i.e. those that are trivially recreated without user interaction.)

I report this because I emptied the cache on a server and this dropped the in the background running webserver using a poetry virtualenv, unbeknownst to me (luckily it was weekend).

So I recommend to set a different default for the virtualenv folder. If you follow XDG specifications that would probably be ~/.local/share/poetry/virtualenvs (FYI: Pipenv already uses ~/.local/share/virtualenvs), and there is probably an similar folder for MacOS.

(Default virtualenvs folder for Windows should probably be fine.)