upgrade_to_latest() doesn't take into account `-o` flag on CLI

[deltamarnix]

HydroMT-Wflow version checks

• I have checked that this issue has not already been reported.
• I have checked that this bug exists on the latest version of HydroMT-Wflow.

Reproducible Example

On branch fix/example-errors, go to upgrade_to_wflow_v1.ipynb and add "-o", "./data/wflow_upgrade/sbm/v1" to the arguments in cell 2. Then try to run the cell.

Current behaviour

You will get an error.

Traceback (most recent call last):
  File "c:\ProgramData\DevDrive\Repos\hydromt_wflow\.pixi\envs\default\Lib\site-packages\hydromt\log.py", line 179, in to_file
    yield
  File "c:\ProgramData\DevDrive\Repos\hydromt_wflow\.pixi\envs\default\Lib\site-packages\hydromt\model\model.py", line 387, in update
    _validate_steps(self, steps)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^
...
    raise TypeError(
        f"Validation of step {i + 1} ({step}) failed because of the following error: {e}"
    )
TypeError: Validation of step 1 (upgrade_to_latest) failed because of the following error: missing a required argument: 'output_dir'

Desired behaviour

It seems that the output_dir can be specified in the yml as an option for that specific argument, but I have already given a -o in the command line, so that should be taken as the output directory if it's empty?

Additional context

No response