Bump Xunit from 2.6.3 to 2.6.4 in /src (#124)

Bumps [Xunit](https://github.com/xunit/xunit) from 2.6.3 to 2.6.4.
- [Commits](xunit/xunit@2.6.3...2.6.4)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Tests/Tests.csproj

@@ -12,7 +12,7 @@
     <PackageReference Include="Verify.DiffPlex" Version="2.3.0" />
     <PackageReference Include="Verify.Xunit" Version="22.10.2" />
     <PackageReference Include="CliWrap" Version="3.6.4" />
-    <PackageReference Include="Xunit" Version="2.6.3" />
+    <PackageReference Include="Xunit" Version="2.6.4" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.5" PrivateAssets="all" />
   </ItemGroup>
 </Project>