add missing codemeta maintainer prooperty

Author: mustafasoylu

src/somesy/codemeta/writer.py

@@ -83,6 +83,17 @@ def authors(self, authors: List[Union[Person, Entity]]) -> None:
         authors_dict = [self._from_person(a) for a in authors]
         self._set_property(self._get_key("authors"), authors_dict)
 
+    @property
+    def maintainers(self):
+        """Return the maintainers of the codemeta.json file."""
+        return self._get_property(self._get_key("maintainers"))
+
+    @maintainers.setter
+    def maintainers(self, maintainers: List[Union[Person, Entity]]) -> None:
+        """Set the maintainers of the project."""
+        maintainers_dict = [self._from_person(m) for m in maintainers]
+        self._set_property(self._get_key("maintainers"), maintainers_dict)
+
     @property
     def contributors(self):
         """Return the contributors of the codemeta.json file."""