Add cooldown configuration to Dependabot updates

Fixes zizmor dependabot-cooldown warnings by adding cooldown
settings (3-day default, 7-day semver-major) to both pip and
github-actions ecosystems.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: AriESQ

.github/dependabot.yml

@@ -4,7 +4,13 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+      cooldown:
+        default-days: 3
+        semver-major-days: 7
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "weekly"
+      cooldown:
+        default-days: 3
+        semver-major-days: 7