Set streambed top elevations using rotated raster

@mnfienen and I are building a modflow model that has a rotated grid using `modflow-setup`. The raster source data we're using to build the model are also rotated (in the same orientation as the model grid). `modflow-setup` is able to use the rotated raster data to build most packages but fails while setting up the SFR package during the the `set_streambed_top_elevations_from_dem` when using the rotated model top raster. It seems like the underlying issue is that the `rasterstats` package [doesn't work with rasters that have rotation coefficients](https://github.com/perrygeo/python-rasterstats/issues/182). In our case, all the minimum elevations for sampled from the dem using the buffered SFR lines are returned as "None". The easiest solution would be to use an unrotated version of the raster for this step, but wondering if you've already come up with a way to handle rotated rasters for `modflow-setup` that might be adapted for `sfrmaker`'s `sample_reach_elevations` function to identify and handle (un-rotate?) rotated DEMs. Happy to help out on this if it the effort seems worthwhile.