bpo-34580: Update sqlite3 examples to call close() explicitly (GH-9079)

The sqlit3.Connection object doesn't call its close() method when it's used
as a context manager.

Doc/includes/sqlite3/row_factory.py

@@ -11,3 +11,5 @@ con.row_factory = dict_factory
 cur = con.cursor()
 cur.execute("select 1 as a")
 print(cur.fetchone()["a"])
+
+con.close()