Bump submodules/vipr from 6ce0d81 to bf1af70

Bumps [submodules/vipr](https://github.com/microsoft/vipr) from `6ce0d81` to `bf1af70`.
- [Release notes](https://github.com/microsoft/vipr/releases)
- [Commits](microsoft/Vipr@6ce0d81...bf1af70)

---
updated-dependencies:
- dependency-name: submodules/vipr
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]