Bump home-assistant/builder from 2021.07.0 to 2021.09.0 (#8)

Bumps [home-assistant/builder](https://github.com/home-assistant/builder) from 2021.07.0 to 2021.09.0.
- [Release notes](https://github.com/home-assistant/builder/releases)
- [Commits](https://github.com/home-assistant/builder/compare/2021.07.0...2021.09.0)

---
updated-dependencies:
- dependency-name: home-assistant/builder
  dependency-type: direct:production
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/builder.yaml

@@ -107,7 +107,7 @@ jobs:
 
       - name: Build ${{ matrix.addon }} add-on
         if: steps.check.outputs.build_arch == 'true'
-        uses: home-assistant/builder@2021.07.0
+        uses: home-assistant/builder@2021.09.0
         with:
           args: |
             ${{ env.BUILD_ARGS }} \