symbolize keys for the Sequel adapter

The "schema_parse_table" method in
lib/sequel/adapters/shared/mysql.rb of Sequel 3.12.1
depends on symbolized keys.

lib/sequel/adapters/mysql2.rb

@@ -191,7 +191,7 @@ module Sequel
       # instead of yielding results for all statements as hashes.
       def fetch_rows(sql, &block)
         execute(sql) do |r|
-          r.each &block
+          r.each(:symbolize_keys => true, &block)
         end
         self
       end