Merge pull request #288 from nathanchance/update-ci-release-20.x

Author: nathanchance

ci.sh

@@ -101,7 +101,7 @@ function do_llvm() {
         --install-target distribution \
         --projects clang lld \
         --quiet-cmake \
-        --ref release/19.x \
+        --ref release/20.x \
         --shallow-clone \
         --show-build-commands \
         --targets X86 \