Fix tests for Gnuk emulation (skip test with no KDF setup).

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

tests/skip_if_gnuk.py

@@ -0,0 +1,6 @@
+import pytest
+
+@pytest.fixture(scope="module",autouse=True)
+def check_gnuk(card):
+    if card.is_gnuk:
+        pytest.skip("Gnuk has no support for those features", allow_module_level=True)