bug: asdf cannot resolve config paths with whitespace in them

[rpdelaney]

From original issue with more context: asdf-ruby/issues/270

If $ASDF_DATA_DIR is set to a path with whitespace in it, the asdf-python plugin cannot do the business:

$ echo $ASDF_DATA_DIR
/Users/ryan/Library/Application Support/asdf
$ asdf install python 3.10.2
Downloading python-build...
fatal: could not create leading directories of '/Users/ryan
Support//asdf/plugins/python/pyenv': Permission denied
$