Closes #1125.

Summary of Changes

• fix mypy error (hopefully)
• add migration for enum annotations to another version, with the possibilities:
  • If the annotation is mapped to a parameter and its type is string and the default string value (if any) is a value expected by the annotation, the annotation will be migrated as expected.
  • If the annotation is mapped to a parameter and its type is known, but not a string, we would assume that the problem of a @enum annotation is solved. E.g., an enum type is created for this parameter.
  • If the annotation is mapped to a parameter, but its type is unknown, an unsure @enum annotation will be created for this parameter.
  • Otherwise, a @todo annotation will be crated instead of the @enum annotation.

Testing Instructions

run the migrate command or view and run the test_migration.py file