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/load_extension.py

@@ -24,3 +24,5 @@
     """)
 for row in con.execute("select rowid, name, ingredients from recipe where name match 'pie'"):
     print(row)
+
+con.close()