github/morello: also explicitly install llvm

The 2023.11 ports tree no longer has llvm-localbase depend on llvm,
so go ahead and install that too.

Author: nwf-msr

.github/workflows/morello.yml

@@ -48,7 +48,7 @@ jobs:
           - os: "morello"
             caps: Purecap
             dependencies: >-
-              llvm-localbase cmake ninja
+              llvm llvm-localbase cmake ninja
             cmake-flags: >
               -DCMAKE_CXX_COMPILER=/usr/local64/bin/clang++
               -DCMAKE_C_COMPILER=/usr/local64/bin/clang