Bump Cake.Testing from 2.0.0 to 3.0.0 in /src

Bumps [Cake.Testing](https://github.com/cake-build/cake) from 2.0.0 to 3.0.0.
- [Release notes](https://github.com/cake-build/cake/releases)
- [Changelog](https://github.com/cake-build/cake/blob/develop/ReleaseNotes.md)
- [Commits](cake-build/cake@v2.0.0...v3.0.0)

---
updated-dependencies:
- dependency-name: Cake.Testing
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

src/Cake.Issues.DupFinder.Tests/Cake.Issues.DupFinder.Tests.csproj

@@ -19,7 +19,7 @@
   <ItemGroup>
     <PackageReference Include="Cake.Issues" Version="2.0.0" />
     <PackageReference Include="Cake.Issues.Testing" Version="2.0.0-beta0001" />
-    <PackageReference Include="Cake.Testing" Version="2.0.0" />
+    <PackageReference Include="Cake.Testing" Version="3.0.0" />
     <PackageReference Include="Shouldly" Version="4.0.3" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.1.118">
       <PrivateAssets>all</PrivateAssets>