python-idna: bump to 3.18

Release notes:
https://github.com/kjd/idna/releases/tag/v3.18

Remove the test for UTS 46 transitional processing, which is now
deprecated and emits a warning. See [1].

[1] https://github.com/kjd/idna/commit/94bcdc38fd75ae8a259132f7e3f5f1fb5373c717

Signed-off-by: Wei-Ting Yang <williamatcg@gmail.com>

lang/python/python-idna/test.sh

@@ -18,6 +18,4 @@ assert idna.alabel('测试') == b'xn--0zwm56d'
 assert idna.encode('Königsgäßchen', uts46=True) == b'xn--knigsgchen-b4a3dun'
 assert idna.decode('xn--knigsgchen-b4a3dun') == 'königsgäßchen'
 
-assert idna.encode('Königsgäßchen', uts46=True, transitional=True) == b'xn--knigsgsschen-lcb0w'
-
 EOF