Revert "gha - opt out Julia Cache"

This reverts commit 210961e.

Julia cache is required to speed up each job. However, the caching mechanism is still a problem as it will throw a warning for each other job than the one which managed to save with action v4

Saving a cache for each buckets would be too heavy in total storage (we are limited to 10Go).

Author: cderv

.github/workflows/test-smokes.yml

@@ -175,8 +175,6 @@ jobs:
           version: "1.11.3"
 
       - name: Cache Julia Packages
-        # FIXME: deactivate julia cache for now
-        if: false
         uses: julia-actions/cache@v2
 
       - name: Restore Julia Packages