Add stub sigstore-param-file.yaml to be updated

To update the file using cURL it needs to exist first, see commit 03042268.

For the failing pipeline see this pipeline.

For the related feature/MR see !77 (merged).

assigned to @klausenbusk

The pipeline can be safely ignored, since it is not supposed to support the releases branch directly. It works only for tags on releases.

approved this merge request

mentioned in commit e8bf1b9c

merged