ci: download lfs modules when building

.forgejo/workflows/push.yaml

@@ -16,6 +16,18 @@ jobs:
     steps:
       # get the repo first
       - uses: https://code.forgejo.org/actions/checkout@v4
+      - name: Checkout LFS
+        run: |
+          UrlBase=$GITHUB_SERVER_URL; \
+          UrlLfsBase=$UrlBase/${{ gitea.repository }}.git/info/lfs/objects; \
+          Auth=`git config --get --local http.$UrlBase/.extraheader`; \
+          git config --local http.${UrlLfsBase}/batch.extraheader "$Auth"; \
+          git config --local http.${UrlLfsBase}/.extraheader ''
+
+          git config --local lfs.transfer.maxretries 1
+
+          git lfs fetch origin refs/remotes/origin/${{ gitea.ref_name }}
+          git lfs checkout
       - name: "Build it locally"
         run: nix build --verbose