Bump akhileshns/heroku-deploy from 3.12.12 to 3.13.15

Bumps [akhileshns/heroku-deploy](https://github.com/akhileshns/heroku-deploy) from 3.12.12 to 3.13.15.
- [Release notes](https://github.com/akhileshns/heroku-deploy/releases)
- [Commits](AkhileshNS/heroku-deploy@v3.12.12...v3.13.15)

---
updated-dependencies:
- dependency-name: akhileshns/heroku-deploy
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.github/workflows/api_deploy.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: akhileshns/heroku-deploy@v3.12.12
+      - uses: akhileshns/heroku-deploy@v3.13.15
         with:
           heroku_api_key: ${{secrets.HEROKU_API_KEY}}
           heroku_email: ${{secrets.HEROKU_EMAIL}}