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/execute_1.py

@@ -14,3 +14,5 @@
 cur.execute("select * from people where name_last=:who and age=:age", {"who": who, "age": age})
 
 print(cur.fetchone())
+
+con.close()