[easy] Make test_mandelbrot_numpy deterministic (pytorch#112042)

It fails for me locally, and I'm not the only one:
https://dev-discuss.pytorch.org/t/main-failing-unit-test-dynamicshapesmisctests/1607

Pull Request resolved: pytorch#112042
Approved by: https://github.com/peterbell10

test/dynamo/test_misc.py

@@ -1682,8 +1682,8 @@ def mandelbrot_numpy(max_iter):
         cnts = torch._dynamo.testing.CompileCounter()
         opt_fn = torch._dynamo.optimize(cnts, nopython=True)(mandelbrot_numpy)
         n_iter = torch._dynamo.config.cache_size_limit
-        for _ in range(n_iter):
-            x = random.randint(2, 30)
+        for i in range(n_iter):
+            x = i + 3
             ref = mandelbrot_numpy(x)
             res = opt_fn(x)
             self.assertEqual(ref, res)