Fix not being able to upload with CLI because the commit_message was …

…not being set

dagshub/upload/wrapper.py

@@ -258,7 +258,7 @@ def upload_files(
         self,
         files: List[FileUploadStruct],
         directory_path: str = "",
-        commit_message: str = DEFAULT_COMMIT_MESSAGE,
+        commit_message: Optional[str] = DEFAULT_COMMIT_MESSAGE,
         versioning: str = "auto",
         new_branch: str = None,
         last_commit: str = None,
@@ -280,6 +280,9 @@ def upload_files(
                 Sets last_commit to be the tip of the branch
         """
 
+        if commit_message is None:
+            commit_message = DEFAULT_COMMIT_MESSAGE
+
         # Truncate the commit message because the max we allow is 100 symbols
         commit_message = commit_message[:100]