Merge pull request #933 from luxonis/fix/imports

Fix imports for depthai_demo

Author: daniilpastukhov

depthai_sdk/src/depthai_sdk/__init__.py

@@ -4,3 +4,5 @@
 from depthai_sdk.oak_device import OakDevice
 from depthai_sdk.replay import *
 from depthai_sdk.record import *
+from depthai_sdk.previews import *
+from depthai_sdk.utils import *