Use nschloe/action-cached-lfs-checkout to retrieve LFS content.

.github/workflows/generate_github_pages.yml

@@ -11,7 +11,8 @@ jobs:
     # Skip in forks
     if: github.repository == 'element-hq/element-x-android'
     steps:
-      - uses: actions/checkout@v4
+      - name: ⏬ Checkout with LFS
+        uses: nschloe/action-cached-lfs-checkout@v1.2.2
       - name: Use JDK 17
         uses: actions/setup-java@v4
         with: