Wait for team histories to save before continuing through saveHistory

Currently we're seeing a number of errors in `saveHistory` that appear to be timeouts. We believe not waiting for the async `saveTeamHistory` function to complete may be resulting in an early termination of the container these functions are supposed to be running in.

functions/src/saveHistory.ts

@@ -23,7 +23,7 @@ export const saveHistory = functions.pubsub
       const teamId = teamDocSnapshot.id;
       const teamDoc = db.collection('teams').doc(teamId);
 
-      saveTeamHistory(timestamp, teamId, teamDoc);
+      await saveTeamHistory(timestamp, teamId, teamDoc);
     }
   });