This action replaces labels at a repository level by renaming them.

It takes an input label-replacement, which is a map of current label name to new name.

Ex.

name: replace-labels
on: 
  workflow_dispatch: {}
permissions: write-all
jobs:

  call-action:
    runs-on: ubuntu-latest
    steps:
      - uses: scanlonp/github-action-replace-labels@main
        id: replace-labels
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          label-replacement: >
            {
              "priority1" : "p1",
              "priority2" : "p2"
            }

This would change the label priority1 to p1, and all issues / PRs with the priority1 label would be updated with the p1 label. Same for priority2 to p2.

The action also has error checking. If any of the keys in the mapping are not current labels in the repository, or any of the values are the names of existing labels, the action will error out before doing any replacement and report the faulty names.