Bump XunitContext from 1.6.0 to 1.8.0 in /src
Bump XunitContext from 1.6.0 to 1.8.0 in /src

Bumps [XunitContext](https://github.com/SimonCropp/XunitContext) from 1.6.0 to 1.8.0.
- [Release notes](https://github.com/SimonCropp/XunitContext/releases)
- [Commits](https://github.com/SimonCropp/XunitContext/commits)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
SimonCropp/NServiceBus.MessagePack