ci: enforce 7-day cooldown on dependabot updates

Give a week for new dependency releases to be vetted before Dependabot opens PRs, reducing exposure to freshly published malicious versions.

Signed-off-by: Benoit Tigeot <benoit.tigeot@lifen.fr>

.github/dependabot.yml

@@ -17,6 +17,8 @@ updates:
           - "k8s.io/cli-runtime"
           - "k8s.io/client-go"
           - "k8s.io/kubectl"
+    cooldown:
+      default-days: 7
   - package-ecosystem: "gomod"
     target-branch: "main"
     directory: "/"
@@ -32,6 +34,8 @@ updates:
           - "k8s.io/cli-runtime"
           - "k8s.io/client-go"
           - "k8s.io/kubectl"
+    cooldown:
+      default-days: 7
   - package-ecosystem: "github-actions"
     target-branch: "main"
     directory: "/"
@@ -41,6 +45,8 @@ updates:
       github-actions:
         patterns:
           - "*"
+    cooldown:
+      default-days: 7
   - # Keep dev-v3 GitHub Actions up to date, while Helm v3 is within support
     package-ecosystem: "github-actions"
     target-branch: "dev-v3"
@@ -51,3 +57,5 @@ updates:
       github-actions:
         patterns:
           - "*"
+    cooldown:
+      default-days: 7