Update Install Python in Mac Doc

[jwokaty]

I don't think we need to brew install python anymore as described in https://github.com/Bioconductor/BBS/blob/devel/Doc/Prepare-macOS-Big-Sur-HOWTO.md#211-install-python-3 since tensorflow is now available for newer python versions, so this section in the documentation needs to be rewritten. Maybe it just needs to be a newer version or install the required dependencies (maybe we should also note what packages require them?). We should also put export PATH=/opt/R/x86_64/bin:$PATH or export PATH=/opt/R/arm64/bin:$PATH in /etc/profile.

Note that brew installing some packages, such as mono and salt may require a version of python to be brew installed and also openssl. In these cases, we should brew uninstall --ignore-dependencies $PACKAGE for the package (maybe brew autoremove too?). If brew install symlinks a brewed python, remove the link with brew unlink $PACKAGE.

Note: without a brewed openssl, it seems that pip3 will fail to update because it needs ssl, which is why we should use the default installed python instead.

On merida1, need to brew uninstall [email protected] and pip3 install dependencies since it is currently showing an ssl error visible at the end of pip3 list.

[hpages]

Yes please get rid of the brewed Python3. It's been a while since we don't need it anymore. See #182 (comment) (from August 2022).

If it comes back as the dependency of something else that we need to brew, and if the installation is "keg-only", then it should not be a problem because "keg-only" means that it won't be in the PATH. So hopefully we won't need to use brew uninstall --ignore-dependencies, which is something we should not use lightly and only as a very last resort.

We should also put export PATH=/opt/R/x86_64/bin:$PATH or export PATH=/opt/R/arm64/bin:$PATH in /etc/profile.

Is this related to Python? If not then maybe we can discuss this in a separate issue?

Thanks

[jwokaty]

More related to #378, which is also related to this issue. I've put it there.