Add parent se_resnext50_32x4d model

Adds a copy of the upstream model used by Trained_model_SM.pth.
This model was downloaded from
http://data.lip6.fr/cadene/pretrainedmodels/se_resnext50_32x4d-a260b3a4.pth
but that website certificate is no longer maintained.
Saving a copy here to ensure long term availability of the model.
See https://github.com/Cadene/pretrained-models.pytorch for more
details on the se_resnext50_32x4d-a260b3a4.pth model.

se_resnext50_32x4d-a260b3a4.pth

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a260b3a40f82dfe37c58d26a612bcf7bef0d27c6fed096226b0e4e9fb364168e
+size 110559176