Add temporary workaround for broken LFS checkout

.gitea/workflows/build.yml

@@ -14,8 +14,19 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v3
-        with:
-          lfs: true
+      # Workaround for broken LFS checkout, see https://gitea.com/gitea/act_runner/issues/164
+      - name: Checkout LFS
+        run: |
+          UrlBase=$GITHUB_SERVER_URL; \
+          UrlLfsBase=$UrlBase/${{ gitea.repository }}.git/info/lfs/objects; \
+          Auth=`/usr/bin/git config --get --local http.$UrlBase/.extraheader`; \
+          /usr/bin/git config --local http.${UrlLfsBase}/batch.extraheader "$Auth"; \
+          /usr/bin/git config --local http.${UrlLfsBase}/.extraheader ''
+
+          git config --local lfs.transfer.maxretries 1
+
+          /usr/bin/git lfs fetch    origin refs/remotes/origin/${{ gitea.ref_name }}
+          /usr/bin/git lfs checkout
       - name: Setup dotnet
         uses: https://github.com/actions/setup-dotnet@v3
         with: