Build the sky resampling right into the sky subtraction so nobody eve…

…r forgets to do it. The sky fiber should always be interpolated onto the science fiber's wavelength solution before sky subtraction, according to the HPF folks.

src/muler/hpf.py

@@ -354,7 +354,7 @@ def sky_subtract(self, method="scalar", scale=0.93):
             raise NotImplementedError
 
         # These steps should propagate uncertainty?
-        sky_estimator = spec.sky.multiply(beta, handle_meta="first_found")
+        sky_estimator = spec.sky_resample().sky.multiply(beta, handle_meta="first_found")
         return spec.subtract(sky_estimator, handle_meta="first_found")
 
     def mask_tellurics(self, method="TelFit", threshold=0.999, dilation=5):