fix: use artifact v3 for GHES compatibility

Gitea (GHES) does not support upload-artifact@v4+.
Revert to v3 which is supported on GHES.

.gitea/workflows/release.yaml

@@ -83,7 +83,7 @@ jobs:
           echo "archive=$stable" >> "$GITHUB_OUTPUT"
 
       - name: Upload build artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v3
         with:
           name: nuwiki-ls-${{ matrix.target }}
           path: ${{ steps.package.outputs.archive }}
@@ -95,12 +95,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Download all build artifacts
-        # upload-artifact@v4 + download-artifact@v4 with merge-multiple
-        # flattens all artifacts into the download path directly.
-        uses: actions/download-artifact@v4
+        # download-artifact@v3 nests each artifact under its own dir
+        # (artifacts/<artifact-name>/<file>), so recurse.
+        uses: actions/download-artifact@v3
         with:
           path: ./artifacts
-          merge-multiple: true
 
       - name: Ensure jq + curl
         run: |