tests/basics/zip: Make skippable.

tests/basics/zip.py

+try:
+    zip
+    set
+except NameError:
+    print("SKIP")
+    import sys
+    sys.exit()
+
 print(list(zip()))
-print(list(zip([1], {2,3})))
+print(list(zip([1], set([2, 3]))))