Bump Cake.Testing from 0.38.1 to 0.38.4 in /Source (#98)

Bumps [Cake.Testing](https://github.com/cake-build/cake) from 0.38.1 to 0.38.4.
- [Release notes](https://github.com/cake-build/cake/releases)
- [Changelog](https://github.com/cake-build/cake/blob/develop/ReleaseNotes.md)
- [Commits](cake-build/cake@v0.38.1...v0.38.4)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Source/Cake.Codecov.Tests/Cake.Codecov.Tests.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="AppVeyor.TestLogger" Version="2.0.0" />
-    <PackageReference Include="Cake.Testing" Version="0.38.1" />
+    <PackageReference Include="Cake.Testing" Version="0.38.4" />
     <PackageReference Include="coverlet.msbuild" Version="2.9.0">
     <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     <PrivateAssets>all</PrivateAssets>