CCM-15866: Address Sonar Findings - Better Perms in Jekyll Container

Author: jamesthompson26-nhs

src/jekyll-devcontainer/src/.devcontainer/Dockerfile

@@ -3,4 +3,11 @@ LABEL org.opencontainers.image.source=https://github.com/NHSDigital/nhs-notify-r
 
 COPY packages.txt packages.txt
 
-RUN apt-get update && xargs apt-get -y install < packages.txt
+USER root
+RUN apt-get update \
+    && xargs apt-get -y install --no-install-recommends < packages.txt \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
+# Run the container as a non-root user by default.
+USER vscode