fix cosign version

Author: konrad2002

.github/workflows/main.yml

@@ -28,9 +28,9 @@ jobs:
     # https://github.com/sigstore/cosign-installer
     - name: Install cosign
       if: github.event_name != 'pull_request'
-      uses: sigstore/cosign-installer@7e0881f8fe90b25e305bbf0309761e9314607e25
+      uses: sigstore/cosign-installer@v3.1.1
       with:
-        cosign-release: 'v1.9.0'
+        cosign-release: 'v2.1.1'
 
     # Workaround: https://github.com/docker/build-push-action/issues/461
     - name: Setup Docker buildx