💬 Fix Slack notification workflow

[Gary-H9]

This relates to this Issue.

I've altered this per my reading of the release notes which include breaking changes for release 2.0.0 of the Slack Workflow which we consume.

I'm unsure if the following code should be the latter:

      - name: Notify Slack on Failure
        if: failure() && steps.terraform_apply.outcome == 'failure'
        id: slack_notification
        uses: slackapi/slack-github-action@485a9d42d3a73031f12ec201c457e2162c45d02d # v2.0.0
        with:
          webhook-type: incoming-webhook
          payload: |
            {
              "run_id": "${{ github.run_id }}",
              "pr_number": "${{ steps.extract_pr.outputs.pr_number }}"
            }
        env:
          SLACK_WEBHOOK_URL: ${{ env.SLACK_WEBHOOK_URL }}

      - name: Notify Slack on Failure
        if: failure() && steps.terraform_apply.outcome == 'failure'
        id: slack_notification
        uses: slackapi/slack-github-action@485a9d42d3a73031f12ec201c457e2162c45d02d # v2.0.0
        with:
          webhook:  ${{ env.SLACK_WEBHOOK_URL }}
          webhook-type: incoming-webhook
          payload: |
            {
              "run_id": "${{ github.run_id }}",
              "pr_number": "${{ steps.extract_pr.outputs.pr_number }}"
            }

[julialawrence]

LGTM

[julialawrence]

LGTM