Fix race condition in benchmark and tokei-metrics workflows

[RAprogramm]

Fix race condition when benchmark and tokei-metrics workflows run in parallel.

Problem

When code changes are pushed to main, both workflows trigger simultaneously:

• benchmark.yml (triggers on src/, benches/, Cargo.toml)
• tokei-metrics.yml (triggers on src/, tests/, benches/**, etc.)

Both workflows:

1. Checkout main
2. Update README.md
3. Commit and push

If they run in parallel, one will fail with:

! [rejected]        main -> main (fetch first)
error: failed to push some refs

Example

Workflow run failed: https://github.com/RAprogramm/cstring-array/actions/runs/18625288263

Solution

Add git pull --rebase origin main before git push in both workflows:

benchmark.yml:179

git commit -m "chore: update benchmark results [skip ci]"
git pull --rebase origin main  # ← ADD
git push

tokei-metrics.yml:159

git commit -m "chore: update tokei metrics [skip ci]"
git pull --rebase origin main  # ← ADD
git push

This ensures both workflows can merge their changes even when running in parallel.

Benefits

• No more failed workflow runs
• Both metrics update successfully
• Race-safe parallel execution