Case-sensitive enum type casts

[niklaskorz]

PR Info

• Closes https://github.com/SeaQL/sea-query/issues/725
• Dependencies:
  • https://github.com/SeaQL/sea-query/pull/789

Bug Fixes

• [x] Filtering on enum fields whose type name was declared case sensitive no longer crashes

Breaking Changes

• [x] Enum names are now case sensitive, i.e. #[sea_orm(enum_name = "MyType")] will result in "MyType" instead of mytype for PostgreSQL.