Added 048 acceptance test

examples/acceptance_tests/048/validators/foo.ak

@@ -0,0 +1,9 @@
+fn when_tuple(a: (Int, Int)) -> Int {
+  when a is {
+    (a, b) -> a
+  }
+}
+
+pub fn spend(a, b, c) -> Bool {
+  when_tuple((4, 1)) == 4
+}