snewpy compatibility issue for flavor transformation.

[waleey]

Changes made to snewpy after the v1.6 version release has significant changes and it breaks ASTERA simulation. For example, I tried to run the following simulation:

model = {'name': 'Nakazato_2013', 'param':{ 'progenitor_mass': 13 * u.Msun, 'revival_time': 300 * [u.ms](http://u.ms/), 'metallicity': 0.004, 'eos': 'shen'} } xform = 'NoTransformation' nmo = 'Normal' sim = Simulation(model=model, distance=10 * u.kpc, Emin=0*u.MeV, Emax=100*u.MeV, dE=1*u.MeV, tmin=-10*u.s, tmax=20*u.s, dt=1*[u.ms](http://u.ms/), mixing_scheme=xform, hierarchy=nmo) sim.run()

And received the following error:

`/Users/walu/icecube/energy_constraints/snecc/snecc_functions.py:1114: SyntaxWarning: invalid escape sequence '\l'
"""
WARNING: QE weights are currently not applied.

---

AttributeError Traceback (most recent call last)
Cell In[12], line 15
9 nmo = 'Normal'
10 sim = Simulation(model=model,
11 distance=10 * u.kpc,
12 Emin=0u.MeV, Emax=100u.MeV, dE=1u.MeV,
13 tmin=-10u.s, tmax=20u.s, dt=1u.ms,
14 mixing_scheme=xform, hierarchy=nmo)
---> 15 sim.run()

File ~/jupyter_env/lib/python3.13/site-packages/asteria/simulation.py:291, in Simulation.run(self, load_simulation)
288 raise NotImplementedError('Simulation loading is not currently implemented')
290 self.compute_photon_spectra()
--> 291 self.compute_energy_per_vol()
292 return

File ~/jupyter_env/lib/python3.13/site-packages/asteria/simulation.py:394, in Simulation.compute_energy_per_vol(self, part_size)
392 if part_size < self.time.size:
393 while idx + part_size < self.time.size:
--> 394 spectrum = self.get_combined_spectrum(self.time[idx:idx + part_size], self.energy, flavor,
395 self._mixing)
396 result[idx:idx + part_size] = np.trapz(spectrum, self.energy.value, axis=1)
397 idx += part_size

File ~/jupyter_env/lib/python3.13/site-packages/asteria/simulation.py:335, in Simulation.get_combined_spectrum(self, t, E, flavor, mixing)
333 if flavor.is_neutrino:
334 if flavor.is_electron:
--> 335 coeffs = mixing.prob_ee(t, E), mixing.prob_ex(t, E)
336 cflavor = Flavor.NU_X
337 else:

AttributeError: 'NoTransformation' object has no attribute 'prob_ee'`

I am using ASTERIA 1.8.0dev and snewpy 1.6, but I had pulled in the changes from a current branch under development.