5.0.0

• Removed support for "Extensible" enums because it felt like a nasty hack till the end.
• Base classes of value objects and smart enums are checks for immutability as well.
• Split Thinktecture.Runtime.Extensions.EntityFrameworkCore into *.EntityFrameworkCore5 and *.EntityFrameworkCore6.
• Added single-item read-only collections/set/dictionary to reduce memory allocations.
• The name of static property "Empty" of a struct-enum is now configurable.
• Analyzer: ValueObjects must be sealed