[#280] Updates rubyzip dependency

Hello,
I noticed a bug in version 1.0.0 of rubyzip that was fixed in a later release. axlsx still uses the buggy version which prevents me from updating the rubyzip gem.

The bug i was talking about:
rubyzip/rubyzip@v1.0.0...v1.1.0#diff-b2465821a9969effeacd35f1d69e18e6L118