github/workflows: fix artifact paths

.github/workflows/user_project_ci.yml

diff --git a/.github/workflows/user_project_ci.yml b/.github/workflows/user_project_ci.yml
index 3b10c08..205a11e 100644
--- a/.github/workflows/user_project_ci.yml
+++ b/.github/workflows/user_project_ci.yml
@@ -67,9 +67,9 @@
         with:
           name: openlane-runs
           path: |
-            /home/runner/work/caravel_user_project/caravel_user_project/openlane/user_proj_example/runs/
-            /home/runner/work/caravel_user_project/caravel_user_project/openlane/user_project_wrapper/runs/
-            /home/runner/work/caravel_user_project/caravel_user_project/gds/
+            ${{ github.workspace }}/openlane/user_proj_example/runs/
+            ${{ github.workspace }}/openlane/user_project_wrapper/runs/
+            ${{ github.workspace }}/gds/
 
       - name: cache gds
         uses: actions/cache@v3
@@ -156,7 +156,7 @@
         with:
           name: precheck-results
           path: |
-            /home/runner/work/caravel_user_project/caravel_user_project/precheck_results/
+            ${{ github.workspace }}/precheck_results/
 
   tapeout:
     needs:
@@ -232,5 +232,5 @@
         with:
           name: caravel-tapeout
           path: |
-            /home/runner/work/caravel_user_project/caravel_user_project/gds/caravel_*.gds
-            /home/runner/work/caravel_user_project/caravel_user_project/signoff/
+            ${{ github.workspace }}/gds/caravel_*.gds
+            ${{ github.workspace }}/signoff/