Bump clang to 18 (#1060)

Forced by this change in JAX build system:
jax-ml/jax#23787

Author: DwarKapex

.github/container/Dockerfile.base

@@ -2,7 +2,7 @@
 ARG BASE_IMAGE=nvidia/cuda:12.6.1-devel-ubuntu22.04
 ARG GIT_USER_NAME="JAX Toolbox"
 ARG [email protected]
-ARG CLANG_VERSION=17
+ARG CLANG_VERSION=18
 
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 ## Obtain GCP's NCCL TCPx plugin