bug: expected fields in evt binary file

[martclanor]

Describe the bug
python version: 3.10.8 (tags/v3.10.8:aaaf517, Oct 11 2022, 16:50:30) [MSC v.1933 64 bit (AMD64)]
numpy version: 1.26.2
flopy version: 3.5.0

When creating evt binary files, there seems to be a bug about the mismatch of the data and header in the _build_data_array function of MFFileAccessList.

To Reproduce
As an example, I use the model: https://github.com/modflowpy/flopy/blob/develop/.docs/Notebooks/mf6_simple_model_example.py
If I insert the following evt package before line 190:

evt = flopy.mf6.modflow.mfgwfevt.ModflowGwfevt(
    gwf,
    stress_period_data={
        0: {
            "data": [((0, 0, 0), 5, 0.0004, 1.0, 1.0)],
            "filename": ".evt_bin",
            "binary": True,
        }
    },
    nseg=1,
    maxbound=1,
    surf_rate_specified=True,
)

I get: ValueError: could not assign tuple of length 7 to structure with 8 fields.

Expected behavior
I do not expect this error because when I export evt as a text file ("binary" flag above set to False), it seems to work fine.

Additional context
I tried looking a bit around and saw the following which might be useful:

• the error is raised in flopy/mf6/data/mffileaccess.py line 1093 when it is attempted to create a numpy array provided the mismatching data and header

return np.array(data_list, dtype=header)

• header (length = 8)
  

• data:
  

• data_list (length = 7):
  

• Not sure but it seems like pxdp and petm are mistakenly included in the header instead of petm0 (which as an MFDataItemStructure object is set to "optional").

Thanks a lot for taking the time to read this.