Update cosign to v2.6.0 and go in the CI to latest version

Change-Id: I1754871a875f82fa1177793e74a41cc88ef4059f
Signed-off-by: Cosmin Cojocar <ccojocar@google.com>

.github/workflows/release.yml

@@ -2,7 +2,7 @@ name: Release
 on:
   push:
     tags:
-      - 'v*'
+      - "v*"
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -17,11 +17,11 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v6
         with:
-          go-version: '1.25.1'
+          go-version: "1.25.1"
       - name: Install Cosign
         uses: sigstore/cosign-installer@v3
         with:
-          cosign-release: 'v2.5.3'
+          cosign-release: "v2.6.0"
       - name: Store Cosign private key in a file
         run: 'echo "$COSIGN_KEY" > /tmp/cosign.key'
         shell: bash