Notify release for native and web

[f1sh1918]

Is your feature request related to a problem? Please describe.
As a dev i want to deploy for native and web/backend separately. Therefore we need to adjust the notify release job because we assume that deb and apk packages are available

Describe the solution you'd like

• Pass a parameter that defines which artifacts must be available to upload depending on which platform you release

[steffenkleinle]

This will be fixed by digitalfabrik/app-toolbelt#15. Instead of passing a parameter to define which assets should be uploaded, I chose to just made the upload more robust and correctly handle if an empty list of files is passed. I tested this here: https://app.circleci.com/pipelines/github/digitalfabrik/entitlementcard/6029/workflows/38c8d3dd-911f-4e2c-a475-52322ab9df01/jobs/43140