Bump rubyzip dependency to 3

[eqladios]

• updated call for Zip::File#open in nuget_spec to use named arguments, should still work fine with <3
• all of the current calls to RubyZip API should work without issues with version >=3, <4
• tests pass successfully

changes:

• bump rubyzip dependency to 3
• update license_finder.gemspec
• update call for Zip::File#open at nuget spec to use named arguments
• no other changes needed to calls for original rubyzip API