use class Foo: instead of class Foo(): (#1797)

* use class Foo: instead of class Foo():

* add ruff linter, copy settings from .flake8 to ruff.toml

test/test_cache_collector.py

@@ -5,7 +5,7 @@ from tinygrad.helpers import dtypes
 from tinygrad.jit import CacheCollector
 from weakref import ref
 
-class FakeDeviceBuffer():
+class FakeDeviceBuffer:
   def __init__(self, sz, dt, device):
     self.size = sz
     self.dtype = dt