fixed FrozenError caused by frozen-string-literal #390
I got FrozenError when I used rubyzip gem with
This PR is to fix the above error.
Linking this up: #374 also tried to address this. Neither PR is a superset of the other, so I'm not sure either one addressed the issue fully, but it is probably all still helping.
I think the best way forward is to get rubocop up to date and enforce the