MAINT: Restore statsmodels to pip-pre (mne-tools#13345)

Author: larsoner

tools/install_pre_requirements.sh

@@ -31,9 +31,8 @@ python -m pip install $STD_ARGS --only-binary ":all:" --default-timeout=60 \
 	"dipy>=1.10.0.dev0" \
 	"pyarrow>=20.0.0.dev0" \
 	"tables>=3.10.3.dev0" \
+	"statsmodels>=0.15.0.dev697" \
 	"h5py>=3.13.0"
-# TODO: should have above: "statsmodels>=0.15.0.dev0"
-# https://github.com/statsmodels/statsmodels/issues/9572
 echo "::endgroup::"
 
 # No Numba because it forces an old NumPy version