Action is using deprecated set-output command

[tiagovrtr]

annotate_pr_with_ruff/annotate_pr_with_ruff/main.py

Line 31 in 6637527

print(f"::set-output name=num_errors::{len(ruff_errors)}")

GitHub is deprecating the set-output command.. Although the feature phase-out is postponed, this needs to be changed to using the $GITHUB_OUTPUT env var