chore(deps): update sigstore/cosign-installer action to v4

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

Author: renovate[bot]

.github/workflows/build-envoy-image-ci.yaml

@@ -103,7 +103,7 @@ jobs:
         tags: quay.io/${{ github.repository_owner }}/cilium-envoy-dev:${{ github.event.pull_request.head.sha }}
 
     - name: Install Cosign
-      uses: sigstore/cosign-installer@d7543c93d881b35a8faa02e8e3605f69b7a1ce62 # v3.10.0
+      uses: sigstore/cosign-installer@faadad0cce49287aee09b3a48701e75088a2c6ad # v4.0.0
 
     - name: Sign Container Image
       run: |

.github/workflows/build-envoy-images-release.yaml

@@ -180,7 +180,7 @@ jobs:
           quay.io/${{ github.repository_owner }}/cilium-envoy:${{ env.ENVOY_PATCH_RELEASE }}-${{ env.SOURCE_TIMESTAMP }}-${{ github.sha }}
 
     - name: Install Cosign
-      uses: sigstore/cosign-installer@d7543c93d881b35a8faa02e8e3605f69b7a1ce62 # v3.10.0
+      uses: sigstore/cosign-installer@faadad0cce49287aee09b3a48701e75088a2c6ad # v4.0.0
 
     - name: Sign Container Image
       run: |