Python parser for UCUM including converter to pint unit library

[dalito]

Since Python had no good parser for UCUM, I created the Python-package ucumvert in Jan-2024.

Today, I made a new Release 0.2.0 to support the latest UCUM version v2.2.

Features:

• Parser for UCUM unit strings that implements the full grammar.
• Converter for creating pint units from UCUM unit strings.
• A pint unit definition file pint_ucum_defs.txt that extends pint´s default units with UCUM units. All UCUM units from the new version 2.2 of the specification are included.