Drop support for Python 3.8

[rsokl]

Dropping support for Python 3.8 allows you to take advantage of features and improvements introduced in Python 3.9 and later versions. Here are some key changes and upgrades you can consider:

1. Type hinting improvements:
   • Use built-in collection types in annotations (e.g., list[int] instead of List[int])
   • Use typing.Annotated for adding context to type hints
2. Dictionary merge (|) and update (|=) operators:
   • Use dict1 | dict2 to merge dictionaries
   • Use dict1 |= dict2 to update dictionaries
3. New string methods:
   • str.removeprefix() and str.removesuffix()
4. New math functions:
   • math.lcm() for least common multiple
   • math.gcd() for greatest common divisor with multiple arguments
5. New functools features:
   • functools.cache() (simpler @lru_cache)
   • functools.topological_sort()
6. Improved decorators:
   • Use @dataclass with kw_only=True parameter
7. Enhanced zoneinfo module for working with time zones
8. Type hinting generics in standard collections
9. More precise error messages for attribute and index access
10. Performance improvements in various areas