follow actions/labeler@v5 config breaking changes

[sensuikan1973]

same with sensuikan1973/libedax4dart#472

[sensuikan1973]

Run ibiqlik/action-yamllint@v3
Run # export LOGFILE=$(mktemp yamllint-XXXXXX)
======================
= Linting YAML files =
======================
./.github/labeler.yml
  4:5       error    wrong indentation: expected [6](https://github.com/sensuikan1973/pedax/actions/runs/7096374305/job/19314790835?pr=1662#step:3:7) but found 4  (indentation)
  10:5      error    wrong indentation: expected 6 but found 4  (indentation)
  16:5      error    wrong indentation: expected 6 but found 4  (indentation)
  [22](https://github.com/sensuikan1973/pedax/actions/runs/7096374305/job/19314790835?pr=1662#step:3:24):5      error    wrong indentation: expected 6 but found 4  (indentation)
  26:5      error    wrong indentation: expected 6 but found 4  (indentation)
  33:5      error    wrong indentation: expected 6 but found 4  (indentation)
  41:5      error    wrong indentation: expected 6 but found 4  (indentation)
  45:5      error    wrong indentation: expected 6 but found 4  (indentation)
  50:5      error    wrong indentation: expected 6 but found 4  (indentation)