add content type

Author: stewartboogert

.github/workflows/buildapptainers.yaml

@@ -68,4 +68,5 @@ jobs:
         with:
           upload_url: ${{ steps.create_release.outputs.upload_url }}
           asset_path: /tmp/${{ matrix.dockerimage }}_develop.sif
-          asset_name: ${{ matrix.dockerimage }}_develop.sif
+          asset_name: ${{ matrix.dockerimage }}_develop.sif
+          asset_content_type: application/octet-stream