Update SNOMED mapping for v2

[fedorov]

Follow up on https://github.com/wasserth/TotalSegmentator/issues/172#issuecomment-1729507681:

If you have some time to have a look at the SNOMED mapping for the new classes that would be great! This is the location of the mapping. I did not change it so far. https://github.com/wasserth/TotalSegmentator/blob/add_nnunetv2/resources/totalsegmentator_snomed_mapping.csv

We will look into this when we get to run the new model! I suggest we keep this issue around until the mapping is updated.