fix: allow specifying an empty string as a Glob

[alestiago]

Description
When using Very Good CLI 0.12.3 doing:

very_good packages get -r --ignore=""

Shows:

Error on line 1, column 1: expected a glob.
  ╷
1 │ 
  │ ^
  ╵

Steps To Reproduce

1. Run very_good packages get -r --ignore="" in a valid directory

Expected Behavior
To accept an empty string as input.

Additional Context
Would simplify feat/support-excluding-directories default parameter.