fix license identifier

Resources
- NGEET/fates#651
- NGEET/fates#650

Author: basnijholt

.zenodo.json

@@ -30,6 +30,6 @@
     "parallel",
     "adaptive active-learning"
   ],
-  "license": "BSD-3-Clause License",
+  "license": "BSD-3-Clause",
   "upload_type": "software"
 }