Raise memory limit for CIFAR test (tinygrad#1499)

Author: g1y5x3

test/models/test_real_world.py

@@ -86,7 +86,7 @@ def train(X):
       loss.backward()
       optimizer.step()
 
-    helper_test("train_cifar", lambda: (Tensor.randn(BS, 3, 32, 32),), train, (1.0/64)*BS, 153)
+    helper_test("train_cifar", lambda: (Tensor.randn(BS, 3, 32, 32),), train, (1.0/48)*BS, 153)
 
     # reset device
     Tensor.training = old_training