feat: use upload_fileobj insted of put_object

Refs: #12

cubicweb_s3storage/storages.py

@@ -102,8 +102,11 @@
             else:
                 upload_key = key
             extra_args = self.get_upload_extra_args(entity, attr, key)
-            self.s3cnx.upload_fileobj(buffer, self.bucket, upload_key,
-                                      ExtraArgs=extra_args)
+
+            put_object_result = self.s3cnx.put_object(Body=buffer,
+                                                      Bucket=self.bucket,
+                                                      Key=upload_key,
+                                                      **extra_args)
             buffer.close()
 
             # when key is suffixed, move to final key in post commit event