Bump containrrr/shoutrrr-action from 1 to 1.0.104

Bumps [containrrr/shoutrrr-action](https://github.com/containrrr/shoutrrr-action) from 1 to 1.0.104.
- [Release notes](https://github.com/containrrr/shoutrrr-action/releases)
- [Commits](containrrr/shoutrrr-action@v1...v1.0.104)

---
updated-dependencies:
- dependency-name: containrrr/shoutrrr-action
  dependency-version: 1.0.104
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]

.github/workflows/release.yml

@@ -39,7 +39,7 @@ jobs:
           GITHUB_TOKEN: ${{ github.token }}
       - name: Post status to Google Chat
         if: ${{ always() }}
-        uses: containrrr/shoutrrr-action@v1
+        uses: containrrr/shoutrrr-action@v1.0.104
         with:
           url: "${{ secrets.WATCHTOWER_NOTIFICATION_URL }}"
           message: "Released `${{ github.repository }}`@`${{ github.sha }}` as ${{ steps.version.outputs.tag }}: *${{ job.status }}*."