Skip dataclassess fields only when None (#180)

Skip dataclassess fields only when `None` to allow to write empty lists,
strings or zeros.

Resolves #179

Author: JCZuurmond

src/databricks/labs/blueprint/installation.py

@@ -570,7 +570,7 @@ def _marshal_dataclass(self, type_ref: type, path: list[str], inst: Any) -> tupl
             if origin is typing.ClassVar:
                 continue
             raw = getattr(inst, field)
-            if not raw:
+            if raw is None:
                 continue
             value, ok = self._marshal(hint, [*path, field], raw)
             if not ok: