Add libomp.so library to rocm artifact

This comes from the `openmp` package on Arch but isn't there for
Ubuntu unless a matching LLVM package happens to be installed.

As the point of the artifact is to run standalone, explicitly add
it.

Author: superm1

.github/workflows/build.yml

@@ -601,6 +601,9 @@ jobs:
           sudo mv /opt/rocm/lib/rocblas/ ./build/bin/
           sudo mv /opt/rocm/lib/hipblaslt/ ./build/bin/
 
+          # Move LLVM OpenMP library
+          sudo mv /opt/rocm/lib/llvm/lib/libomp.so* ./build/bin/
+
       - name: Fetch system info
         id: system-info
         run: |