better font for matplotlib

[grzanka]

This pull request includes changes to the write method in the pymchelper/writers/plots.py file to improve error handling and formatting. The most important changes include updating the string formatting method, enhancing logging, and adding error handling for plot saving.

Enhancements to string formatting and logging:

• Changed the string formatting for output_filename to use f-strings for better readability.
• Updated the logging statement to use a more efficient logging method.

Improved error handling:

• Added a try-except block to handle ValueError when saving plots, including logging the error and attempting to save the plot with a different font configuration.