Don't require auth for local rstudio server

.devcontainer/Dockerfile

@@ -22,6 +22,8 @@ RUN --mount=type=cache,target=/var/cache/apt \
 RUN rm -rf /usr/library/lib/R/site-library/*
 # copy the renv directory into the local site library from the OpenSAFELY R action image
 COPY --chown=rstudio:rstudio --from=ghcr.io/opensafely-core/r:latest /renv/lib/R-4.0/x86_64-pc-linux-gnu/ /usr/local/lib/R/site-library
+# Configure RStudio Server to run without auth
+RUN echo "auth-none=1" >> /etc/rstudio/rserver.conf && echo "USER=rstudio" >> /etc/environment
 
 # Copy the Python virtualenv from OpenSAFELY Python action image
 COPY --from=ghcr.io/opensafely-core/python:v2 /opt/venv /opt/venv