1.34.0

• update only_throw_errors to not report on values of type Never
• update prefer_mixin to handle class mixins
• update unnecessary_null_checks to ignore Future.value and Completer.complete
• fix unnecessary_parenthesis false positives on constant patterns
• new lint: invalid_case_patterns
• update unnecessary_const to handle case patterns
• improve handling of null-aware cascades in unnecessary_parenthesis
• update unreachable_from_main to report unreachable public static fields, getters, setters, and methods, that are declared on public classes, mixins, enums, and extensions