Remove redundant Microsoft.AspNetCore.Http.Abstractions package reference

Fixes NU1510 error in Fitnet.Contracts.Infrastructure project. The package is already included via FrameworkReference to Microsoft.AspNetCore.App.

Co-authored-by: kamilbaczek <74410956+kamilbaczek@users.noreply.github.com>

Author: Copilot

Chapter-3-microservice-extraction/Fitnet.Contracts/Src/Fitnet.Contracts.Infrastructure/Fitnet.Contracts.Infrastructure.csproj

@@ -8,7 +8,6 @@
     <PackageReference Include="MassTransit" />
     <PackageReference Include="MassTransit.RabbitMQ" />
     <PackageReference Include="MediatR" />
-    <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" />
     <PackageReference Include="Microsoft.EntityFrameworkCore" />
     <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" />
   </ItemGroup>