Update anchore/sbom-action action to v0.20.4 (#192)

| datasource  | package             | from    | to      |
| ----------- | ------------------- | ------- | ------- |
| github-tags | anchore/sbom-action | v0.20.2 | v0.20.4 |

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -62,7 +62,7 @@ jobs:
       run: dotnet test --configuration Release --logger:"GitHubActions;report-warnings=false"
 
     - name: Generate SBOM
-      uses: anchore/sbom-action@cee1b8e05ae5b2593a75e197229729eabaa9f8ec # v0.20.2
+      uses: anchore/sbom-action@7b36ad622f042cab6f59a75c2ac24ccb256e9b45 # v0.20.4
       if: runner.os == 'Windows'
       with:
         artifact-name: grafana-opentelemetry-dotnet.spdx.json