chore(*.psql/*.sql): update all *.psql to *.sql files

queries/selects/top_artists.psql

@@ -1,13 +0,0 @@
-SELECT
-  l.artist_name,
-  TO_CHAR(COUNT(l.id), 'FM999,999,999') AS total_listens
-FROM
-  optimized_listens l
-WHERE
-  EXTRACT(YEAR FROM TO_TIMESTAMP(l.listened_at)) = EXTRACT(YEAR FROM CURRENT_DATE)
-  AND l.artist_name IS NOT NULL
-GROUP BY
-  l.artist_name
-ORDER BY
-  COUNT(l.id) DESC
-LIMIT 10;