docs: edit artifact.delete docstring return type

Author: anancarv

pyartifactory/objects/artifact.py

@@ -363,7 +363,6 @@ def move(self, artifact_current_path: str, artifact_new_path: str, dryrun: bool
     def delete(self, artifact_path: str) -> None:
         """
         :param artifact_path: Path to file in Artifactory
-        :return: bool
         """
         artifact_path = artifact_path.lstrip("/")
         self._delete(f"{artifact_path}")