Bump stringstream from 0.0.5 to 0.0.6

Bumps [stringstream](https://github.com/mhart/StringStream) from 0.0.5 to 0.0.6.
- [Release notes](https://github.com/mhart/StringStream/releases)
- [Commits](mhart/StringStream@v0.0.5...v0.0.6)

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