python: Fix a test for newer GnuPG (>= 2.3).

* lang/python/tests/t-quick-subkey-creation.py: Specify RSA.

--

Using GnuPG 2.3, a key with default (ed25519/cv25519) cannot have some
combination of capabilities (e.g., "encr auth").

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

lang/python/tests/t-quick-subkey-creation.py

@@ -70,7 +70,8 @@ with support.EphemeralContext() as ctx:
             continue
 
         res = ctx.create_subkey(
-            key, sign=sign, encrypt=encrypt, authenticate=authenticate)
+            key, sign=sign, encrypt=encrypt, authenticate=authenticate,
+            algorithm="rsa")
         subkey = get_subkey(res.fpr)
         assert sign == subkey.can_sign
         assert encrypt == subkey.can_encrypt