Speed up conda installation

[bouweandela]

Pin some lower versions of packages to make it easier for conda to solve the environment. See ESMValGroup/ESMValCore#660 and #1676.

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Tasks

• Create an issue to discuss what you are going to do, if you haven't done so already (and add the link at the bottom)
• Give this pull request a descriptive title that can be used as a one line summary in a changelog
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• Please use yamllint to check that your YAML files do not contain mistakes

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[valeriupredoi]

Have you used these forcings to build the new conda package @bouweandela ?

[valeriupredoi]

about the new conda package - am a happy camper, well done Bouwe! 🍺 A few remarks:

• it is much much faster!
• it still consumes considerable amounts of RAM: up to 2GB even more; on a machine with 4GB max and running other stuff (eg the absolutely inefficient Firefox) it'll struggle, we should probably mention this
• I am still getting the dlopen error but that's just my ancient Ubuntu
• I think it's still useful to keep a footnote a la: if your conda is struggling, install esmvalcore first (the previous PR)
• in case of a rollback-ed installation (eg one forgets to install and link julia) there are a lot of ClobberError's since conda doesn't remove the __pycache__ dirs: lib/python3.7/site-packages/esmvaltool/diag_scripts/zmnam/__pycache__/zmnam_preproc.cpython-37.pyc will persist, we should give a pro tip for the real pros to remove all these useless dirs
• very nice and convenient once the R packages are installed with one installation even if it rolls back and doesn't install the esmvaltool package, those compiled and made R packages are used for a second time try of installation and no need to watch cc1plus take forever and half again
• I still need to install it on Jasmin too (can't log in at the mo) but it worked really well on my ancient box so 👍 🍺

[bouweandela]

Have you used these forcings to build the new conda package @bouweandela ?

Yes

I think it's still useful to keep a footnote a la: if your conda is struggling, install esmvalcore first (the previous PR)

Let's discuss that in the other PR. It might work some of the time, but it might not work other times, it's conda.

in case of a rollback-ed installation (eg one forgets to install and link julia) there are a lot of ClobberError's since conda doesn't remove the pycache dirs: lib/python3.7/site-packages/esmvaltool/diag_scripts/zmnam/pycache/zmnam_preproc.cpython-37.pyc will persist, we should give a pro tip for the real pros to remove all these useless dirs

This shouldn't be a problem, since conda will hopefully overwrite those files with identical copies. Apparently it is not able to completely roll back the installation.

[valeriupredoi]

yes and yes, and good stuff again! 🍺