Pin eslint-plugin-react and switch to node 16 lts to allow build to succeed

eslint-plugin-react was just updated and seems to have a bug which breaks our build. To fix this, we can temporarily pin the version of this module in package.json. Here is the relevant bug report on GitHub:

https://github.com/yannickcr/eslint-plugin-react/issues/3215

Simultaneously, there seems to be some other new breakage related to node version 17, which we are currently using in our images. Even with the above pinning, build is failing for our project with node 17. Node 17 is the "current" release and is not recommended by node for production apps anyway. Node 16 is the "LTS" release and is recommended for production, and it also happens to build our app successfully. So we switch to node 16 in this merge request as well.

Also, our gitlab-ci pipeline was using an unpinned version of the node container, so that is also sort of a bug.