fix docker images

Dockerfile

@@ -1,11 +1,11 @@
 #See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging.
 
-FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-buster-slim AS base
+FROM mcr.microsoft.com/dotnet/aspnet:3.1-buster-slim AS base
 WORKDIR /app
 EXPOSE 80
 EXPOSE 443
 
-FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS publish
+FROM mcr.microsoft.com/dotnet/sdk:3.1-buster AS publish
 COPY ./src/ ./src/
 RUN dotnet publish "/src/BirdsiteLive/BirdsiteLive.csproj" -c Release -o /app/publish
 RUN dotnet publish "/src/BSLManager/BSLManager.csproj" -r linux-x64 --self-contained true -p:PublishSingleFile=true -p:IncludeAllContentForSelfExtract=true -c Release -o /app/publish