simplify mypy config

cwlupgrader/main.py

@@ -737,7 +737,7 @@ def hints_and_requirements_clean(document: Dict[str, Any]) -> None:
                 document[section] = new_section
 
 
-def shorten_type(type_obj: List[Any]) -> Union[str, List[Any]]:
+def shorten_type(type_obj: Union[str, List[Any]]) -> Union[str, List[Any]]:
     """Transform draft-3 style type declarations into idiomatic v1.0 types."""
     if isinstance(type_obj, str) or not isinstance(type_obj, Sequence):
         return type_obj

mypy.ini

@@ -1,24 +1,7 @@
 [mypy]
+strict = True
 show_error_context = true
 show_column_numbers = true
 show_error_codes = true
 pretty = true
-
-# --strict options as of mypy 0.910
-warn_unused_configs = True
-disallow_any_generics = True
-disallow_subclassing_any = True
-disallow_untyped_calls = True
-disallow_untyped_defs = True
-disallow_incomplete_defs = True
-check_untyped_defs = True
-disallow_untyped_decorators = True
-no_implicit_optional = True
-warn_redundant_casts = True
-warn_unused_ignores = True
-warn_return_any = True
-implicit_reexport = False
-strict_equality = True
-
-[mypy-ruamel.*]
-ignore_errors = True
+warn_unreachable = True