update models_class1_pan_variants download

mhcflurry/downloads.yml

@@ -30,7 +30,9 @@ releases:
               default: false
 
             - name: models_class1_pan_variants
-              url: https://www.dropbox.com/s/ry67t6l7n5kaa2r/models_class1_pan_variants.20191011.tar.bz2?dl=1
+              part_urls:
+                - https://github.com/openvax/mhcflurry/releases/download/1.4.0/models_class1_pan_variants.20191101.tar.bz2.part.aa
+                - https://github.com/openvax/mhcflurry/releases/download/1.4.0/models_class1_pan_variants.20191101.tar.bz2.part.ab
               default: false
 
             - name: data_mass_spec_benchmark