Incompatible `rcParams` with Newer Matplotlib Versions

[MichZampetakis]

The current style files (e.g., load_style('jupyter')) include several matplotlib.rcParams keys that are no longer valid in modern Matplotlib versions (3.6+). This results in runtime KeyError or ValueError exceptions when applying styles.

These errors originate from:
~pyOPALTools/opal/visualization/styles/default.py

Errors Encountered:

1. Invalid lines.marker value:
   ValueError: Key lines.marker: Supported markers are [string, int]

Cause:

mpl.rcParams['lines.marker'] = None 

None is no longer accepted — should use '' or 'None'.

2. Removed rcParam:
   KeyError: 'mathtext.fallback_to_cm is not a valid rc parameter'

3. Removed rcParam:
   KeyError: 'savefig.jpeg_quality is not a valid rc parameter'

Proposed fix:
Guard deprecated or removed keys before setting them:

if 'savefig.jpeg_quality' in mpl.rcParams:
    mpl.rcParams['savefig.jpeg_quality'] = 95

Or more generally:

def safe_set_rcparam(key, value):
    if key in matplotlib.rcParams:
        matplotlib.rcParams[key] = value

Then replace direct assignments with:

safe_set_rcparam('lines.marker', '')
safe_set_rcparam('mathtext.fallback_to_cm', True)
safe_set_rcparam('savefig.jpeg_quality', 95)

This would probably restore compatibility with modern Matplotlib versions while maintaining backward compatibility.

Environment:
Python version: 3.9.6
Matplotlib version: 3.9.4