ci(dependabot): Configure cooldown

To address the "insufficient cooldown" warning surfaced
by zizmor code scanning.

Author: ValuedMammal

.github/dependabot.yml

@@ -1,18 +1,21 @@
 version: 2
-enable-beta-ecosystems: true   
+enable-beta-ecosystems: true
 
 updates:
-  
+
   - package-ecosystem: github-actions
     directory: "/"
     schedule:
-      interval: daily     
-      time: "03:00"       
-   
+      interval: daily
+      time: "03:00"
+    cooldown:
+      default-days: 7
+
   - package-ecosystem: cargo
     directory: "/"
     schedule:
       interval: weekly
       day: monday
       time: "04:00"
- 
+    cooldown:
+      default-days: 7