Fix CI issues (#676)

This definition causes problems with newer CCCL versions. As we don't actually use it ourselves, go ahead and drop it to fix CI

Authors:
  - https://github.com/jakirkham

Approvers:
  - Gregory Lee (https://github.com/grlee77)

URL: #676

python/cucim/src/cucim/skimage/_vendored/_ndimage_filters_core.py

@@ -190,7 +190,6 @@ def _call_kernel(
 
 template<> struct std::is_floating_point<float16> : std::true_type {};
 template<> struct std::is_signed<float16> : std::true_type {};
-template<class T> struct std::is_signed<complex<T>> : std::is_signed<T> {};
 """