Add ability to show version (and not download) when parsing version from version.tf file

[ocofaigh]

Is your feature request related to a problem? Please describe.
tfswitch --show-latest will always display the latest version. However it seems there is no way to display the version that would be installed when reading from a version.tf file without actually installing it:

% tfswitch              
Reading required version from terraform file
Reading required version from constraint: >= 1.3, < 1.4
Matched version: 1.3.9

Describe the solution you'd like
Looking for a flag to be able to output 1.3.9 from above example without actually downloading it

[MatrixCrawler]

Solved with #416
Use --dry-run flag to determine the version