Fix and update CI

[muzimuzhi]

• Fix l3build check failure caused by enlarged default value for maxprintline (from 79 to 9999) see https://github.com/latex3/l3build/blob/main/CHANGELOG.md\#2023-03-22
• Update workflow rule for deprecated GitHub Actions commands set-output and env Node 12
• Change on.pull_request.branches: [main] to on.pull_request.branches: [master] because current repo uses master as default branch, and there's no main branch

Before: Workflow run failed with 2 warnings (see failed workflow run https://github.com/muzimuzhi/gbt7714-bibtex-style/actions/runs/4636467931/attempts/1) After: Workflow run passed with 0 warnings.

[zepinglee]

Thanks!

[muzimuzhi]

BTW, I spot the failed CI on recent branch cqupt, see https://github.com/zepinglee/gbt7714-bibtex-style/actions/runs/4356394340.

Perhaps the changes in https://github.com/zepinglee/gbt7714-bibtex-style/commit/4b138cbad62f727d7ef08dff7b33fb74313707dd would help with debugging. It was once contained in current PR but then removed due to a bit off-topic.