Example dos does not work

[jacopotagliabue]

Steps to reproduce:

• clone the repo
• python -m venv venv and source venv/bin/activate
• pip install convoys==0.2.1
• python examples/dob_violations.py

Stacktrace:

File "examples/dob_violations.py", line 50, in
run()
File "examples/dob_violations.py", line 25, in run
convoys.plotting.plot_cohorts(G, B, T, model=model, ci=0.95,
File "/Users/jacopotagliabue/Documents/repos/convoys/venv/lib/python3.8/site-packages/convoys/plotting.py", line 62, in plot_cohorts
m.fit(G, B, T)
File "/Users/jacopotagliabue/Documents/repos/convoys/venv/lib/python3.8/site-packages/convoys/multi.py", line 31, in fit
self.base_model.fit(X, B, T)
File "/Users/jacopotagliabue/Documents/repos/convoys/venv/lib/python3.8/site-packages/convoys/regression.py", line 269, in fit
for i, _ in enumerate(sampler.sample(p0, iterations=n_iterations)):
File "/Users/jacopotagliabue/Documents/repos/convoys/venv/lib/python3.8/site-packages/emcee/ensemble.py", line 379, in sample
self.backend.grow(iterations, state.blobs)
File "/Users/jacopotagliabue/Documents/repos/convoys/venv/lib/python3.8/site-packages/emcee/backends/backend.py", line 175, in grow
a = np.empty((i, self.nwalkers, self.ndim), dtype=self.dtype)
TypeError: 'numpy.float64' object cannot be interpreted as an integer