(maint) Add Pwsh to Dev Container

The release process uses PowerShell to deploy the release.  This commit adds
PowerShell to the development container so releases can be done from inside the
container.

Author: glennsarti

.devcontainer/Dockerfile

@@ -17,7 +17,9 @@ ARG USER_UID=1000
 ARG USER_GID=$USER_UID
 
 # Configure apt and install packages
-RUN apt-get update \
+RUN wget https://packages.microsoft.com/config/debian/10/packages-microsoft-prod.deb \
+    && dpkg -i packages-microsoft-prod.deb \
+    && apt-get update \
     && apt-get -y install --no-install-recommends apt-utils dialog 2>&1 \
     # Verify git, process tools installed
     && apt-get -y install git openssh-client less iproute2 procps lsb-release \
@@ -26,6 +28,9 @@ RUN apt-get update \
     && gem install ruby-debug-ide \
     && gem install debase \
     #
+    # Install PowerShell
+    && apt-get install -y powershell \
+    #
     # Create a non-root user to use if preferred - see https://aka.ms/vscode-remote/containers/non-root-user.
     && groupadd --gid $USER_GID $USERNAME \
     && useradd -s /bin/bash --uid $USER_UID --gid $USER_GID -m $USERNAME \