fix: not copyable

[halowahyudi]

Thank you for helping to make this package better!

Please make sure you've read CONTRIBUTING.md
before submitting your pull request, and that you have:

• provided a rationale for your change (I try not to add features that are going to have a limited user-base)
• used the PSR-2 Coding Standard
• added tests
• documented any change in behaviour (e.g. updated the README.md, etc.)
• only submitted one pull request per feature

Thank you!

[cviebrock]

Missed this ... thanks @halowahyudi !