Add default shell, avoid dpkg stderr messages

.devcontainer/Dockerfile

@@ -5,16 +5,25 @@
 
 FROM php:7-cli
 
+# Configure apt
+ENV DEBIAN_FRONTEND=noninteractive
+RUN apt-get update \
+    && apt-get -y install --no-install-recommends apt-utils 2>&1
+
 # Install xdebug
 RUN yes | pecl install xdebug \
 	&& echo "zend_extension=$(find /usr/local/lib/php/extensions/ -name xdebug.so)" > /usr/local/etc/php/conf.d/xdebug.ini \
 	&& echo "xdebug.remote_enable=on" >> /usr/local/etc/php/conf.d/xdebug.ini \
 	&& echo "xdebug.remote_autostart=on" >> /usr/local/etc/php/conf.d/xdebug.ini
 
-# Install git, process tools
-RUN apt-get update && apt-get -y install git procps
+# 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