Add missing dataclass decorator

This is needed for mypy, otherwise the use of fields()
is flagged.

Author: enzbang

src/e3/spdx.py

@@ -114,6 +114,7 @@ def to_json_dict(self) -> dict[str, Any]:
         return {self.json_entry_key: self.value}
 
 
+@dataclass
 class SPDXSection:
     """Describe a SPDX section."""