Bump Verify.Xunit from 21.0.0 to 21.1.0 in /src

Bumps [Verify.Xunit](https://github.com/VerifyTests/Verify) from 21.0.0 to 21.1.0.
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](VerifyTests/Verify@21.0.0...21.1.0)

---
updated-dependencies:
- dependency-name: Verify.Xunit
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

src/DiffEngineTray.Tests/DiffEngineTray.Tests.csproj

@@ -10,7 +10,7 @@
  <PackageReference Include="Argon" Version="0.9.0" />
  <PackageReference Include="Verify.DiffPlex" Version="2.2.1" />
  <PackageReference Include="Verify.WinForms" Version="4.0.0" />
- <PackageReference Include="Verify.Xunit" Version="21.0.0" />
+ <PackageReference Include="Verify.Xunit" Version="21.1.0" />
  <PackageReference Include="Verify.ImageMagick" Version="3.2.2" />
  <PackageReference Include="Xunit" Version="2.5.0" />
  <PackageReference Include="xunit.runner.visualstudio" Version="2.5.0" PrivateAssets="all" />