Building from source requires `gnu-tar` on macOS

[FlorianLoch]

Creating the npm-licenses.tar.bz2 makes use of the --transform flag, which bsdtar being shipped with macOS does not support.

find $(REACT_APP_NODE_MODULES_PATH) -iname "license*" | tar cfj $(REACT_APP_NPM_LICENSES_TARBALL) --transform 's/^/npm_licenses\//' --files-from=-

It's neat - but is it actually necessary? 🤔

Of course, can be mitigated by installing gnu-tar and preferring it in the path. Perhaps, if the transform is actually necessary, this could be added as build requirement?
I know, it says non-exhaustive list - but my hope would be to find a way around it 😉