fix random types (#1301)

Author: gus-massa

typed-racket-lib/typed-racket/base-env/base-env.rkt

@@ -92,7 +92,7 @@
 
 ;; Section 4.3.2.7 (Random Numbers)
 [random
-  (cl->* (->opt -Int -Int [-Pseudo-Random-Generator] -NonNegFixnum)
+  (cl->* (->opt -Int -Int [-Pseudo-Random-Generator] -Int)
          (->opt -Int [-Pseudo-Random-Generator] -NonNegFixnum)
          (->opt [-Pseudo-Random-Generator] -Flonum))]
 

typed-racket-test/unit-tests/typecheck-tests.rkt

@@ -2182,7 +2182,9 @@
                 (pseudo-random-generator->vector pg))
               (-vec* -PosInt -PosInt -PosInt -PosInt -PosInt -PosInt))
         (tc-e (random 1 5 (make-pseudo-random-generator))
-              -NonNegFixnum)
+              -Integer)
+        (tc-e (random -1 -5 (make-pseudo-random-generator))
+              -Integer)
 
         ;Structure Type Properties
         (tc-e (make-struct-type-property 'prop)