fix(dep): remove invalid vtk dep

trame_vtk/__init__.py

@@ -1,3 +1,14 @@
 from trame_client.utils.version import get_version
 
 __version__ = get_version("trame-vtk")
+
+
+def reference_id(ref):
+    if ref:
+        try:
+            return ref.__this__[1:17]
+        except Exception:
+            id_str = str(ref)[-12:-1]
+            # print('====> fallback ID %s for %s' % (id_str, ref))
+            return id_str
+    return "0x0"

trame_vtk/widgets/vtk/common.py

@@ -5,7 +5,7 @@
 from trame_client.widgets.core import AbstractElement
 
 from trame_vtk.modules import common
-from trame_vtk.modules.vtk.serializers.utils import reference_id
+from trame_vtk import reference_id
 
 try:
     import zlib  # noqa