Set default shell, avoid dpkg warnings

.devcontainer/Dockerfile

@@ -5,10 +5,19 @@
 
 FROM mcr.microsoft.com/dotnet/core/sdk:2.1
 
-# Install git, process tools
+# Configure apt
-RUN apt-get update && apt-get -y install git procps
+ENV DEBIAN_FRONTEND=noninteractive
+RUN apt-get update \
+    && apt-get -y install --no-install-recommends apt-utils 2>&1
+
+# Install git, process tools, lsb-release (common in install instructions for CLIs)
+RUN apt-get -y install git procps lsb-release
 
 # Clean up
 RUN apt-get autoremove -y \
     && apt-get clean -y \
     && rm -rf /var/lib/apt/lists/*
+ENV DEBIAN_FRONTEND=dialog
+
+# Set the default shell to bash rather than sh
+ENV SHELL /bin/bash