tests/multi_net: Skip SSL test if relevant modules aren't available.

Signed-off-by: Damien George <damien@micropython.org>

tests/multi_net/ssl_data.py

@@ -1,7 +1,11 @@
 # Simple test creating an SSL connection and transferring some data
 # This test won't run under CPython because it requires key/cert
 
-import ubinascii as binascii, usocket as socket, ussl as ssl
+try:
+    import ubinascii as binascii, usocket as socket, ussl as ssl
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 PORT = 8000