Simplify Firestore isAdmin rule

firestore.rules

@@ -6,10 +6,12 @@ service cloud.firestore {
   match /databases/{database}/documents {
 
     function isAdmin() {
-      return request.auth.uid == 'igi2zGXsfxYPgB0DJTXVJVmwCOr2' // Austin
-             || request.auth.uid == '5LZ4LgYuySdL1huCWe7bti02ghx2' // James
-             || request.auth.uid == 'tlmGNz9kjXc2EteizMORes4qvWl2' // Stephen
-             || request.auth.uid == 'IPTOzEqrpkWmEzh6hwvAyY9PqFb2' // Manifold
+      return request.auth.token.email in [
+        'akrolsmir@gmail.com',
+        'jahooma@gmail.com',
+        'taowell@gmail.com',
+        'manticmarkets@gmail.com'
+      ]
     }
 
     match /stats/stats {