framework: update checkout.

Submodule framework 12c10e5..6af0b65:
  > hooks/fancy: print_prefix_text, report_try{,_end}: make all output under try-done blocks indented.
  > scripts/shell: runner: exempt nested runners from dry-run, do not log commands in dry-run.
  > scripts/shell: runner: improve logging, make message types semantically correct and less cluttered.
  > scripts/shell: runner: fix nested runners, make RUNNER_FD local.