Limit 'superuser' status of current moderators (#386)

Resolves MOD-88

Co-authored-by: Geometrically <18202329+Geometrically@users.noreply.github.com>

src/models/users.rs

@@ -77,4 +77,11 @@ impl Role {
             Role::Moderator | Role::Admin => true,
         }
     }
+
+    pub fn is_admin(&self) -> bool {
+        match self {
+            Role::Developer | Role::Moderator => false,
+            Role::Admin => true,
+        }
+    }
 }