Split rocm back out of bundle (#6432)

We're over budget for github's maximum release artifact size with rocm + 2 cuda
versions.  This splits rocm back out as a discrete artifact, but keeps the layout so it can
be extracted into the same location as the main bundle.

.github/workflows/release.yaml

@@ -475,6 +475,7 @@ jobs:
           (cd dist; find . -type f | xargs sha256sum > ../sha256sum.txt)
           mv sha256sum.txt dist/
           mv dist/linux-???64 .
+          mv dist/linux-amd64-rocm .
           cat dist/sha256sum.txt
       - name: Create or update Release
         run: |