CI: Pin actions to hashes

.github/workflows/reusable-test.yml

@@ -55,7 +55,7 @@ jobs:
     steps:
 
       - name: Download repository archive
-        uses: actions/download-artifact@v8
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c  # v8
         with:
           name: ${{ inputs.archive }}
           path: ${{ github.workspace }}
@@ -67,7 +67,7 @@ jobs:
           ls -lsha
 
       - name: Cache $CCACHE_DIR
-        uses: actions/cache@v5
+        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae  # v5
         env:
           CACHE_KEY: ${{ env.CACHE_BASE_KEY }}-ccache2
         with:
@@ -99,7 +99,7 @@ jobs:
 
       - name: Upload code coverage data
         if: ${{ inputs.dev-gcov }}
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7
         with:
           path: ${{ github.workspace }}/repo/obj_coverage/verilator-${{ inputs.suite }}.info
           name: code-coverage-${{ inputs.suite }}