Fix GDF NumPy >= 2

[cbrnr]

Fixes #12907.

[cbrnr]

This fixes the issue encountered e.g. with this dataset.

However, and this is likely unrelated, I was wondering why the log contains next(self.gen):

>>> raw = mne.io.read_raw("/Users/clemens/Downloads/S01_MI/motorimagination_subject1_run1.gdf")
Extracting EDF parameters from /Users/clemens/Downloads/S01_MI/motorimagination_subject1_run1.gdf...
GDF file detected
Setting channel info structure...
Could not determine channel type of the following channels, they will be set as EEG:
F3, F1, Fz, F2, F4, FFC5h, FFC3h, FFC1h, FFC2h, FFC4h, FFC6h, FC5, FC3, FC1, FCz, FC2, FC4, FC6, FTT7h, FCC5h, FCC3h, FCC1h, FCC2h, FCC4h, FCC6h, FTT8h, C5, C3, C1, Cz, C2, C4, C6, TTP7h, CCP5h, CCP3h, CCP1h, CCP2h, CCP4h, CCP6h, TTP8h, CP5, CP3, CP1, CPz, CP2, CP4, CP6, CPP5h, CPP3h, CPP1h, CPP2h, CPP4h, CPP6h, P3, P1, Pz, P2, P4, PPO1h, PPO2h, eog-l, eog-m, eog-r, thumb_near, thumb_far, thumb_index, index_near, index_far, index_middle, middle_near, middle_far, middle_ring, ring_near, ring_far, ring_little, litte_near, litte_far, thumb_palm, wrist_bend, roll, pitch, gesture, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy, armeodummy
Creating raw.info structure...
/Users/clemens/.local/share/uv/python/cpython-3.12.7-macos-aarch64-none/lib/python3.12/contextlib.py:144: RuntimeWarning: Channel names are not unique, found duplicates for: {'armeodummy'}. Applying running numbers for duplicates.
  next(self.gen)

Or is it just my setup?

[larsoner]

Thanks @cbrnr !

[cbrnr]

I forgot to add the "backport-candidate" label to this PR (I just slapped it on the issue), so I assume this has not been backported automatically?

[larsoner]

@meeseeksdev backport to maint/1.8