[CI] Update RAPIDS to latest stable (#78)

Co-authored-by: hcho3 <2532981+hcho3@users.noreply.github.com>

Author: token-generator-for-automated-prs[bot]

containers/ci_container.yml

@@ -4,7 +4,7 @@
 # containers/dockerfile/Dockerfile.CONTAINER_DEF
 
 x-rapids_versions:
-  stable: &rapids_version "25.12"
+  stable: &rapids_version "26.04"
 
 x-cuda_versions:
   cuda: &cuda_version "12.9.0"