Fix broken downgrade test

Author: nefrathenrici

config/model_configs/single_column_precipitation_test.yml

@@ -19,5 +19,5 @@ toml: [toml/single_column_precipitation_test.toml]
 diagnostics:
   - short_name: [hus, clw, cli, husra, hussn, ta, wa]
     period: 500secs
-  - short_name: [pr, ]
+  - short_name: [pr]
     period: 10secs