[CI] get correct binary related to #585

as there is now a amd64 and an arm64 we cannot relate on a generic wildcard anymore

Author: ramonskie

ci/tasks/prepare-docker-workspace/task.yml

@@ -25,4 +25,4 @@ run:
   - |
     cp -R ./bosh-bootloader docker-workspace/
     cp "./dockerfiles/${DOCKERFILE}" docker-workspace/
-    cp ./bbl-cli-dev/bin/bbl-*linux* docker-workspace/bbl
+    cp ./bbl-cli-dev/bin/bbl-*linux_amd64 docker-workspace/bbl