Safe to remove readthedocs.yml and requirements.txt?

[kmpaul]

With the merge of #167, it seems that we do not need to keep the readthedocs.yml file nor the ci/environment_pip.txt (i.e., requirements.txt) file. However, I don't want to delete these resources if they are needed for existing/old PRs, for example. Is it safe to remove these files?

(Regarding the old PRs, my question really comes down to whether the CI configuration files are read from the PR branch/fork or from the main branch. I think they are read from the PR branch, which means deleting these files shouldn't break anything.)