Use a 14-day Dependabot cooldown (#1121)

Delay dependency updates beyond the highest-risk window immediately after release.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: ce6aeb0a-6210-4716-8a84-2f3e7555625f

Author: bschnurr

.github/dependabot.yml

@@ -8,4 +8,5 @@ updates:
     schedule:
       interval: 'weekly'
     cooldown:
-      default-days: 7
+      # Delay updates beyond the highest-risk window after a release.
+      default-days: 14