Update sigstore/cosign-installer action to v3.9.0

Author: renovate[bot]

.github/workflows/main.yml

@@ -77,7 +77,7 @@ jobs:
       # https://github.com/sigstore/cosign-installer
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@v3.7.0
+        uses: sigstore/cosign-installer@v3.9.0
 
       # Set up BuildKit Docker container builder to be able to build
       # multi-platform images and export cache