do not use getenv('PTX') in tests (#12095)

* test without ptx

* fix tests

* fix test

* linters

test/test_tensor.py

@@ -9,7 +9,7 @@ from extra.gradcheck import numerical_jacobian, jacobian, gradcheck
 from hypothesis import given, settings, strategies as strat
 from tinygrad.device import is_dtype_supported
 from tinygrad.uop.ops import Ops, UOp
-from tinygrad.runtime.support.compiler_cuda import PTX
+from tinygrad.renderer.ptx import PTXRenderer
 from tinygrad.codegen import full_rewrite
 from tinygrad.dtype import DType
 
@@ -915,7 +915,7 @@ class TestIdxUpcast(unittest.TestCase):
   def test_regular_sym(self):
     self.do_op_then_assert(dtypes.int, 2048, 2048, UOp.variable("dim3", 1, 64).bind(32))
 
-  @unittest.skipIf(PTX, "PTX always convert Ops.INDEX to int64")
+  @unittest.skipIf(isinstance(Device[Device.DEFAULT].renderer, PTXRenderer), "PTX always convert Ops.INDEX to int64")
   def test_symfold(self):
     # This would cause an overflow, but after sym fold it's within int32
     a = Tensor.arange(65535)