Updated MVC app to .NET 5

Signed-off-by: GitHub <noreply@github.com>

aspnet-mssql/app/aspnetapp/Dockerfile

@@ -0,0 +1,17 @@
+
+FROM mcr.microsoft.com/dotnet/aspnet:5.0 as base
+WORKDIR /app
+
+FROM mcr.microsoft.com/dotnet/sdk:5.0 AS build
+COPY . /src
+WORKDIR /src
+RUN ls
+RUN dotnet build "aspnetapp.csproj" -c Release -o /app/build
+
+FROM build AS publish
+RUN dotnet publish "aspnetapp.csproj" -c Release -o /app/publish
+
+FROM base AS final
+WORKDIR /app
+COPY --from=publish /app/publish .
+ENTRYPOINT ["dotnet", "aspnetapp.dll"]