chore(deps): bump mattermost/action-mattermost-notify

Bumps [mattermost/action-mattermost-notify](https://github.com/mattermost/action-mattermost-notify) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/mattermost/action-mattermost-notify/releases)
- [Commits](mattermost/action-mattermost-notify@2.0.0...v2.1.0)

---
updated-dependencies:
- dependency-name: mattermost/action-mattermost-notify
  dependency-version: 2.1.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/mattermost.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.actor != 'dependabot[bot]' }}
     steps:
-      - uses: mattermost/action-mattermost-notify@2.0.0
+      - uses: mattermost/action-mattermost-notify@v2.1.0
         with:
           MATTERMOST_WEBHOOK_URL: ${{ secrets.MATTERMOST_WEBHOOK_URL }}
           TEXT: "Pull request opened: [${{ github.event.pull_request.title }}](${{ github.event.pull_request.html_url }})"