progress: move past the progress line after each section

Before this change, the progress line was written over byt he next unrelated output and some part of it could remains visible.

Example faulty output::

Authenticated to "https://auth.softwareheritage.org/auth/".
Ready to scan tests
Files:                     16Software Heritage archive
            known:         16 (100%)
directories:                2
      fully-known:          2 (100%)
  partially-known:          0 (  0%)