Update vinyl-source-stream requirement from ^1.0.0 to ^2.0.0
Update vinyl-source-stream requirement from ^1.0.0 to ^2.0.0

Updates the requirements on [vinyl-source-stream](https://github.com/hughsk/vinyl-source-stream) to permit the latest version.
- [Release notes](https://github.com/hughsk/vinyl-source-stream/releases)
- [Commits](https://github.com/hughsk/vinyl-source-stream/commits/v2.0.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
fengtingzhang/heroku-node-bower,fengtingzhang/heroku-node-bower