FIX: restrict scipy to >=1.17 and update Legendre code

[carleyjmartin]

Scope

This PR updates the pyDARN code to use the new version of the scipy.special Legendre function 'assoc_legendre_p_all' instead of the old deprecated 'lpmn' function that was replaced in version 1.15.0, but was broken for a while and is now fixed in the latest 1.17 version of scipy.
The outputs for the new legendre functions are very different, so to reduce the changes in the code I have reworked the new output to be as similar to the old one as possible.

I tested the new code with scipy 1.15-1.16.3 but I got the issue we had before, so we would need to restrict up to 1.17 for this to work.

With the new code change, it doesn't make sense to keep the old code and if/else it as we still need to have a <1.15 >=1.17 statement anyway, where <1.15 is now 2.5+ years old anyway.

issue: to close #434

Approval

Number of approvals: 2 for testing please

Test

matplotlib version: 3.10.8
python version: 3.11
Note testers: please indicate what version of matplotlib you are using

import pydarn
import matplotlib.pyplot as plt

date_file = '/home/carleyjm/data/map/20251001.n.map'
map_data,_ = pydarn.read_map(date_file)

plt.figure(figsize=(10,10))
pydarn.Maps.plot_mapdata(map_data, record=3, contour_fill = True, color_vectors=False, coastline=True)
plt.show()

Comparison between old code and scipy 1.14.0 and new code and 1.17.0:
OLD:

NEW:

[alexchartier]

Looks good to me