Bump xunit-dotnet monorepo to v3 (#962)

| datasource | package                     | from  | to    |
| ---------- | --------------------------- | ----- | ----- |
| nuget      | xunit.v3                    | 2.0.3 | 3.0.0 |
| nuget      | xunit.v3.extensibility.core | 2.0.3 | 3.0.0 |

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Directory.Packages.props

@@ -19,7 +19,7 @@
     <PackageVersion Include="xunit.abstractions" Version="2.0.3" />
     <PackageVersion Include="xunit.extensibility.execution" Version="2.9.3" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.1" />
-    <PackageVersion Include="xunit.v3" Version="2.0.3" />
-    <PackageVersion Include="xunit.v3.extensibility.core" Version="2.0.3" />
+    <PackageVersion Include="xunit.v3" Version="3.0.0" />
+    <PackageVersion Include="xunit.v3.extensibility.core" Version="3.0.0" />
   </ItemGroup>
 </Project>