Fix zizmor workflow findings

Author: samdark

.github/dependabot.yml

@@ -16,3 +16,5 @@ updates:
     schedule:
         interval: "daily"
     versioning-strategy: increase-if-necessary
+    cooldown:
+      default-days: 7

.github/workflows/zizmor.yml

@@ -14,8 +14,8 @@ on:
       - '.github/**.yaml'
 
 permissions:
-  actions: read
-  contents: read
+  actions: read # Required by zizmor when reading workflow metadata through the API.
+  contents: read # Required to read workflow files.
 
 jobs:
   zizmor: