mcv: update cosign to v3.0.4

Signed-off-by: Maryam Tahhan <mtahhan@redhat.com>

Author: maryamtahhan

.github/workflows/mcv-build-example-images.yml

@@ -162,7 +162,7 @@ jobs:
       - name: Install Cosign
         uses: sigstore/cosign-installer@v4.0.0
         with:
-          cosign-release: v3.8.1
+          cosign-release: v3.0.4
       - name: Check install!
         run: cosign version