fix(cicd): add cosign installer

.github/workflows/sfp-build-docker.yml

@@ -37,13 +37,15 @@ jobs:
       contents: read
       packages: write
       id-token: write 
-      
+
     steps:
 
     - uses: actions/checkout@v2
       with:
         fetch-depth: 0
 
+    - name: Install Cosign
+      uses: sigstore/[email protected]
 
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v3