Unittests fail on master

[FynnFreyer]

As the title says.

Steps to reproduce

• clone repo
  git clone https://github.com/veg/hivclustering && cd hivclustering
• activate venv (with an old python, so we can install the right numpy version)
  python3.8 -m venv venv && source venv/bin/activate
• install nose, bioext build dependencies, and hivclustering (with edge filtering extensions, just to be sure)
  pip install nose numpy==1.20.3 biopython cython && pip install .[edgefiltering]
• run tests
  nosetests tests/centrality.py

Expected result

It runs the tests, without errors.

Actual result

.F
======================================================================
FAIL: Ensure degrees are correct
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/fynn/RKI/Sandbox/hivclustering/venv/lib64/python3.8/site-packages/nose/case.py", line 198, in runTest
    self.test(*self.arg)
  File "/home/fynn/RKI/Sandbox/hivclustering/tests/centrality.py", line 63, in test_degrees
    assert set(patients) == set(expected)
AssertionError

----------------------------------------------------------------------
Ran 2 tests in 0.033s

FAILED (failures=1)