message: Update callbacks.py
  Mirrored cl/358287618
  Fixes GitHub
diff: @@ -1207,8 +1207,9 @@ class ModelCheckpoint(Callback):
  decision to overwrite the current save file is made based on either
  the maximization or the minimization of the monitored quantity.
  For `val_acc`, this should be `max`, for `val_loss` this should be
  - `min`, etc. In `auto` mode, the direction is automatically inferred
  - from the name of the monitored quantity.
  + `min`, etc. In `auto` mode, the mode is set to `max` if the quantities
  + monitored are 'acc' or start with 'fmeasure' and are set to `min` for
  + the rest of the quantities.
  save_weights_only: if True, then only the model's weights will be saved
  (`model.save_weights(filepath)`), else the full model is saved
  (`model.save(filepath)`).
  