ci: Use clang-20 for sanitizer tasks

ci/test/01_base_install.sh

@@ -49,7 +49,7 @@ if [ -n "$PIP_PACKAGES" ]; then
 fi
 
 if [[ ${USE_MEMORY_SANITIZER} == "true" ]]; then
-  ${CI_RETRY_EXE} git clone --depth=1 https://github.com/llvm/llvm-project -b "llvmorg-19.1.6" /msan/llvm-project
+  ${CI_RETRY_EXE} git clone --depth=1 https://github.com/llvm/llvm-project -b "llvmorg-20.1.0-rc1" /msan/llvm-project
 
   cmake -G Ninja -B /msan/clang_build/ \
     -DLLVM_ENABLE_PROJECTS="clang" \