[github][ci][clang] add clang 16, 17, 18 to the list

Author: travisg

.github/workflows/github-ci-clang.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        toolchain-ver: [14, 15]
+        toolchain-ver: [14, 15, 16, 17, 18]
         debug: [2, 0]
         project:
           # Note: Clang toolchains do not ship with a compiler-rt (libgcc) for