[KED-1749] `fsspec.filesystem` doesn't (reliably) expose `pathsep` property

Description

Cannot save a list of figures

Steps to Reproduce

On kedro ipython:

from kedro.extras.datasets.matplotlib import MatplotlibWriter
import matplotlib.pyplot as plt
lp = MatplotlibWriter(filepath='mab_list')
plots = []
for i in range(5):
    plots.append(plt.figure())
    plt.plot([1,2,3], [4,5,6+i])
    plt.close()
lp.save(plots)

Expected Result

Create a folder named mab_list with 5 PNG files.

Actual Result

DataSetError: Failed while saving data to data set MatplotlibWriter(filepath=mab_list, protocol=file).
'LocalFileSystem' object has no attribute 'pathsep'

Fix

I just changed .pathsep by .sep in line: https://github.com/quantumblacklabs/kedro/blob/32180557299a196b82a7d1ad7bf93d94627e1a3e/kedro/extras/datasets/matplotlib/matplotlib_writer.py#L169

Your Environment

Include as many relevant details about the environment in which you experienced the bug:

• Kedro version used (pip show kedro or kedro -V): Version: 0.16.1
• Python version used (python -V): Python 3.8.3
• Operating system and version: mcOS Catalina 10.15.5

[lorenabalan]

Closing this as resolved, will be be available in the next release. 😃

[DmitriiDeriabinQB]

@saludes Yes, that was clear from your comment. Let me make the issue title less confusing 🙂