Bump MSTest.TestFramework from 3.0.2 to 3.1.1

Bumps [MSTest.TestFramework](https:/microsoft/testfx) from 3.0.2 to 3.1.1.
- [Release notes](https:/microsoft/testfx/releases)
- [Changelog](https:/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v3.0.2...v3.1.1)

---
updated-dependencies:
- dependency-name: MSTest.TestFramework
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

MessagePack.NodaTime.Tests/MessagePack.NodaTime.Tests.csproj

@@ -12,7 +12,7 @@
  <Version>3.0.2</Version>
  </PackageReference>
  <PackageReference Include="MSTest.TestFramework">
- <Version>3.0.2</Version>
+ <Version>3.1.1</Version>
  </PackageReference>
  <PackageReference Include="xunit">
  <Version>2.4.2</Version>