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This way user can repeat just the first and last cell to get both versions.

Previously protein got computed and shown in both cases but only
saved to the downloaded zip when relaxation was done.

Colab is easily broken by openmm and other software messing with locale.
This mitigation patch lets the %shell and ! work again.
It is much stronger solution than just avoiding shell when making zip.

* Python 3.8 is now what we get in Colab, use it in our Conda as well
* Fix imports, make some unconditional - chain of depencencies makes them
  needed even for relax_prediction==False
* Mitigate spurious error "A UTF-8 locale is required. Got ANSI_X3.4-1968"
  which makes all shell commands defunct - use shutil.make_archive()