Bump github.com/stretchr/testify from 1.6.1 to 1.7.0

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.6.1 to 1.7.0.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](https://github.com/stretchr/testify/compare/v1.6.1...v1.7.0

)

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