add additional todo comments

Author: kratsg

src/pyhf/optimize/mixins.py

@@ -87,6 +87,8 @@ def _internal_postprocess(
         tensorlib, _ = get_backend()
 
         # TODO: check how to handle this for batching
+        # TODO: handle skipping fixed parameters
+        # TODO: handle various backends
         for par_index, (fitted_par, bound) in enumerate(zip(fitresult.x, par_bounds)):
             if fitted_par in bound:
                 log.warning(f'parameter at index {par_index} is at the bounds')