Fix missing install step in notebooks for documentation (Colab support)

[AndrewSazonov]

Fixes #134

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.04%. Comparing base (5a82427) to head (aeabe24).
⚠️ Report is 7 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #135   +/-   ##
=======================================
  Coverage   82.04%   82.04%           
=======================================
  Files         133      133           
  Lines        6916     6916           
  Branches      581      581           
=======================================
  Hits         5674     5674           
  Misses       1037     1037           
  Partials      205      205           

Flag	Coverage Δ
integration	68.50% <ø> (ø)
unittests	71.54% <ø> (ø)

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