Cache snapcraft, but move the cache data into ~/ first

.github/workflows/build.yml

@@ -318,12 +318,26 @@ jobs:
       - name: Restore cache - snapcraft
         uses: actions/cache@v3
         with:
-          path: /root/.cache/snapcraft
+          path: ~/snapcraft-cache
           key: snapcraft-cache
 
+      - name: Move cache from home to root
+        run: |
+          mkdir -p /root/.cache
+          if [[ -d "~/snapcraft-cache" ]]; then
+            mv ~/snapcraft-cache /root/.cache/snapcraft
+            chown -R root:root /root/.cache/snapcraft
+            echo "moved cache from home to root"
+          fi
+
       - name: Build snap
         run: sudo snapcraft --use-lxd
 
+      - name: Move cache root to home
+        run: |
+          mv /root/.cache/snapcraft ~/snapcraft-cache
+          chown -R $USER:$USER ~/snapcraft-cache
+
       - uses: actions/upload-artifact@v3
         with:
           name: snapcraft-build