fix: replacing avg for sum in queries

crates/proof-of-sql/examples/movies/main.rs

@@ -118,9 +118,12 @@ fn main() {
         &verifier_setup,
     );
 
-    // Query 3: Calculate the average duration of movies by genre
+    // Query 3: Calculate the total duration and count of movies by genre
+    // Note: We're using SUM and COUNT instead of AVG because the current version
+    // of the SQL parser doesn't support the AVG function. You can calculate the
+    // average by dividing total_duration by movie_count.
     prove_and_verify_query(
-        "SELECT genre, AVG(duration) AS avg_duration FROM movies GROUP BY genre ORDER BY avg_duration DESC",
+        "SELECT genre, SUM(duration) AS total_duration, COUNT(*) AS movie_count FROM movies GROUP BY genre ORDER BY total_duration DESC",
         &accessor,
         &prover_setup,
         &verifier_setup,