Binder notebooks broken with sample data

[lauraporta]

Describe the bug
When loading a binder notebook that contain sample data the cell that is supposed to load fails

To Reproduce
Run on binder this example 👉🏻 https://derotation.neuroinformatics.dev/examples/core_function.html

Expected behaviour
It should be able to access the tiff file and the .npy file

Log file
Output:

---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
Cell In[3], line 3
      1 angles_path = data_folder / "angles_per_line.npy"
      2 print(f"Loading per-line rotation angles from {angles_path}")
----> 3 angles_per_line = np.load(angles_path)  # Shape: (height,)

File /srv/conda/envs/notebook/lib/python3.10/site-packages/numpy/lib/_npyio_impl.py:451, in load(file, mmap_mode, allow_pickle, fix_imports, encoding, max_header_size)
    449     own_fid = False
    450 else:
--> 451     fid = stack.enter_context(open(os.fspath(file), "rb"))
    452     own_fid = True
    454 # Code to distinguish from NumPy binary files and pickles.

FileNotFoundError: [Errno 2] No such file or directory: '/home/jovyan/notebooks/examples/data/angles_per_line.npy'

Computer used (please complete the following information):
Python3.10 kernel on binder

[lauraporta]

Fixed by #47