Fix a unit test for map.el

* test/automated/map-tests.el (test-map-let): Fix the test to work
with the new syntax of `map-let'.

test/automated/map-tests.el

@@ -322,9 +322,9 @@ Evaluate BODY for each created map.
     (should (= foo 1))
     (should (= bar 2))
     (should (null baz)))
-  (map-let ((foo . a)
-            (bar . b)
-            (baz . c)) '((foo . 1) (bar . 2))
+  (map-let (('foo a)
+            ('bar b)
+            ('baz c)) '((foo . 1) (bar . 2))
     (should (= a 1))
     (should (= b 2))
     (should (null c))))