build(deps): Bump MSTest.TestFramework from 3.0.4 to 3.1.1 (#256)

Bumps [MSTest.TestFramework](https://github.com/microsoft/testfx) from 3.0.4 to 3.1.1.
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v3.0.4...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]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/ReactiveMarbles.PropertyChanged.SourceGenerator.Tests/ReactiveMarbles.PropertyChanged.SourceGenerator.Tests.csproj

@@ -13,7 +13,7 @@
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.11.0" PrivateAssets="all" />
     <PackageReference Include="System.Reactive" Version="6.0.0" />
     <PackageReference Include="FluentAssertions" Version="6.2.0" />
-    <PackageReference Include="MSTest.TestFramework" Version="3.0.4" />
+    <PackageReference Include="MSTest.TestFramework" Version="3.1.1" />
     <PackageReference Include="MSTest.TestAdapter" Version="3.1.1" />    
   </ItemGroup>