Add a caching step for image optimizations

.github/workflows/jekyll.yml

@@ -43,11 +43,21 @@ jobs:
       - name: Setup Pages
         id: pages
         uses: actions/configure-pages@v5
+      - name: Restore optimized images from cache
+        uses: actions/cache/restore@v4
+        with:
+          path: ./_site/assets/img
       - name: Build with Jekyll
         # Outputs to the './_site' directory by default
         run: bundle exec jekyll build --baseurl "${{ steps.pages.outputs.base_path }}"
         env:
           JEKYLL_ENV: production
+      - name: Save images to cache
+        if: steps.cache-unity.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: ./_site/assets/img
+          key: images
       - name: Upload artifact
         # Automatically uploads an artifact from the './_site' directory by default
         uses: actions/upload-pages-artifact@v3