Add ror for UMich

Apparently affiliations are required to have something called an 'ror'. I was able to find the one for UMich: https://ror.org/search?query=university+of+michigan%2C+ann+arbor

Author: nlharris

_data/operations.yml

@@ -117,6 +117,7 @@ members:
   wikidata: Q125208044
 - affiliation:
     name: University of Michigan, Ann Arbor, MI
+    ror: 00jmfr291
   country: USA
   github: zhengj2007
   groups: