Fix optional import, release 1.2.1

[timokau]

Description

Fixing critical bug #137.

Motivation and Context

As @kiudee said so fittingly in #137, "This should definitely not happen".

How Has This Been Tested?

Pre-commit hooks & test suite. We should do #139 at some point.

Does this close/impact existing issues?

Fixes #137

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.

[codecov[bot]]

Codecov Report

Merging #138 into master will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #138   +/-   ##
=======================================
  Coverage   59.96%   59.96%           
=======================================
  Files         116      116           
  Lines        7658     7658           
=======================================
  Hits         4592     4592           
  Misses       3066     3066           

Impacted Files	Coverage Δ
csrank/__init__.py	100.00% <100.00%> (ø)