Add breaking change Slack notifier

[AyodeAwe]

Sends a notification to a designated Slack channel on every PR labelled with breaking, whenever any of the following events are triggered on the PR:

• closed
• reopened
• labeled
• unlabeled

This shared-workflow would be consumed in the following manner:

name: Trigger Breaking Change Notifications

on:
  pull_request:
    types:
      - closed
      - reopened
      - labeled
      - unlabeled

jobs:
  trigger-notifier:
    if: contains(toJSON(github.event.pull_request.labels.*.name), 'breaking')
    secrets: inherit
    uses: rapidsai/shared-workflows/.github/workflows/breaking-change-alert.yaml@<branch>
    with:
      sender_login: ${{ github.event.sender.login }}
      sender_avatar: ${{ github.event.sender.avatar_url }}
      repo: ${{ github.repository }}
      pr_number: ${{ github.event.pull_request.number }}
      pr_title: ${{ github.event.pull_request.title }}
      pr_body: ${{ github.event.pull_request.body || '_Empty PR description_' }}
      pr_base_ref: ${{ github.event.pull_request.base.ref }}
      pr_author: ${{ github.event.pull_request.user.login }}
      event_action: ${{ github.event.action }}
      pr_merged: ${{ github.event.pull_request.merged }}

Example run:

• Workflow run: https://github.com/rapidsai/literate-octo-potato/actions/runs/11615937445/job/32347710850?pr=854
• PR used: https://github.com/rapidsai/literate-octo-potato/pull/854

[AyodeAwe]

After this PR is approved/merged, I will open follow up PRs in all the relavant RAPIDS repositories.

[KyleFromNVIDIA]

I'm guessing the logic for calculating what constitutes a "breaking change" is not present in this workflow, but is left for the individual repos to decide? And this workflow just sends the Slack notification?

I see now that this workflow will be applied to PRs with the breaking label. I don't see a reference to a label event here, so I assume the logic of invoking the workflow on PRs with the label is left to the repos.

[AyodeAwe]

I don't see a reference to a label event here, so I assume the logic of invoking the workflow on PRs with the label is left to the repos.

Thanks for the review @KyleFromNVIDIA.

Note this in the description of this PR:

name: Trigger Breaking Change Notifications

on:
  pull_request:
    types:
      - closed
      - reopened
      - labeled
      - unlabeled

# ...rest of the worfklow

Once this PR is approved and merged, I will open PRs across all RAPIDS repositories with that labelled event included, just as described in the PR description.

[AyodeAwe]

@KyleFromNVIDIA any further thoughts?