Support new release policy

According to the new release policy repository URL now looks like 

```
https://download.tarantool.org/tarantool/pre-release/series-2/ubuntu/dists/focal/main/binary-amd64/Packages
```

The API of this action should be extended somehow to support the new workflow.

See also https://github.com/tarantool/tarantool/discussions/6182