chore: script workspaces from package.json on publishing

[MasterOdin]

Closes #101

PR modifies the publish workflow such that a new helper script will be called before publishing to strip out the workspaces value in the package.json file, and a post publish step that restores the original package.json file. This avoids publishing the package with this additional key that causes a warning in yarn, but should otherwise not affect any other part of the dev flow.

To test, can run:

$ npm run prepublishOnly
# should have modified package.json & package.json.bak
$ npm run postpublish
# should only have original package.json

[CLAassistant]

All committers have signed the CLA.

[kdy1]

Thanks!