Use of btoa in the browser prevents use of Unicode characters #12

Describe the bug

When pushing data that has Unicode points in the browser, btoa is used to encode the file content to be sent to GitHub, which does not handle those characters.

To Reproduce

gitrows.put(path, { test: '🙂' })

Expected behavior

Unicode points should be converted to base64 both in the browser and Node.js.

Shameless plug, I made the following package for universal conversion to solve similar issues in the past: @47ng/codec.