Bump Microsoft.Extensions.DependencyInjection.Abstractions in /src (#883

)

Bumps [Microsoft.Extensions.DependencyInjection.Abstractions](https://github.com/dotnet/runtime) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/dotnet/runtime/releases)
- [Commits](dotnet/runtime@v5.0.0...v6.0.0)

---
updated-dependencies:
- dependency-name: Microsoft.Extensions.DependencyInjection.Abstractions
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

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

src/Whipstaff.Core/Whipstaff.Core.csproj

@@ -9,7 +9,7 @@
     <PackageReference Include="MediatR.Extensions.Microsoft.DependencyInjection" Version="9.0.0" />
     <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="2.2.0" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Abstractions" Version="6.0.0" />
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="5.0.0" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="6.0.0" />
   </ItemGroup>