Undo unnecessary hack

Author: znichollscr

Database/input-data/supplementary-source-id-info.yaml

@@ -137,5 +137,4 @@ UofMD-landState-3-0:
     These have been addressed in v3.1.
     As a result, v3.0 has been retracted.
 UofMD-landState-3-1:
-  doi: 10.25981/ESGF.input4MIPs.CMIP7/2521499
   license_id: CC BY 4.0