use stretch-slim to consisten with debug image

Author: adashen

content/dotnet-template-azure-iot-edge-module/CSharp/Dockerfile.amd64

@@ -7,11 +7,11 @@ RUN dotnet restore
 COPY . ./
 RUN dotnet publish -c Release -o out
 
-FROM microsoft/dotnet:2.1-runtime-alpine
+FROM microsoft/dotnet:2.1-runtime-stretch-slim
 WORKDIR /app
 COPY --from=build-env /app/out ./
 
-RUN adduser -Ds /bin/sh moduleuser
+RUN useradd -ms /bin/bash moduleuser
 USER moduleuser
 
 ENTRYPOINT ["dotnet", "SampleModule.dll"]