Update user_project_ci.yml

.github/workflows/user_project_ci.yml

diff --git a/.github/workflows/user_project_ci.yml b/.github/workflows/user_project_ci.yml
index 9d9ee71..2b8c246 100644
--- a/.github/workflows/user_project_ci.yml
+++ b/.github/workflows/user_project_ci.yml
@@ -39,7 +39,7 @@
       - name: populate pdk cache
         uses: actions/cache@v3
         with:
-          path: $PDK_ROOT
+          path: ${{ env.PDK_ROOT }}
           key: ${{ runner.os }}-pdk-${{ github.run_id }}
 
   user_project_flow_gf180mcuC:
@@ -66,10 +66,10 @@
       - name: Export OPENLANE ROOT
         run: echo "OPENLANE_ROOT=/home/runner/work/AS2650/openlane" >> $GITHUB_ENV
           
-      - name: restore src cache
+      - name: restore pdk cache
         uses: actions/cache@v3
         with:
-          path: $PDK_ROOT
+          path: ${{ env.PDK_ROOT }}
           key: ${{ runner.os }}-pdk-${{ github.run_id }}
 
       - name: Install dependencies