3.0.0

• Dropped support for Python 3.8 @agronholm
• Changed nullable relationships to include Optional in their type annotations @sheinbergon
• Fixed SQLModel code generation @sheinbergon
• Fixed two rendering issues in ENUM columns when a non-default schema is used: an unwarranted positional argument and missing the schema argument @agronholm
• Fixed AttributeError when metadata contains user defined column types @agronholm
• Fixed AssertionError when metadata contains a column type that is a type decorator with an all-uppercase name @agronholm
• Fixed MySQL DOUBLE column types being rendered with the wrong arguments @agronholm