build(deps): bump slackapi/slack-github-action from 1 to 2

Bumps [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action) from 1 to 2.
- [Release notes](https://github.com/slackapi/slack-github-action/releases)
- [Commits](slackapi/slack-github-action@v1...v2)

---
updated-dependencies:
- dependency-name: slackapi/slack-github-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/infracost.yml

@@ -91,7 +91,7 @@ jobs:
           echo "::set-output name=diffTotalMonthlyCost::$(jq '(.diffTotalMonthlyCost // 0) | tonumber' /tmp/infracost.json)"
 
       - name: Send cost estimate to Slack
-        uses: slackapi/slack-github-action@v1
+        uses: slackapi/slack-github-action@v2
         if: ${{ inputs.slack_notification == 'true' }}
         with:
           payload: ${{ steps.infracost-slack.outputs.slack-message }}