Updated packages in R image

In order to add a new package to the R Docker image we had to upgrade some of the existing package versions. Hopefully these upgrades will be welcome but there’s a small possibility they might cause issues with existing code so please be on the look out for this.

The most significant upgrade is of the readr package from 1.3.1 to 2.1.4. You can find the changelog here: https://readr.tidyverse.org/news/index.html

You can see the full list of upgraded packages on Github here: https://github.com/opensafely-core/r-docker/commit/30fc019