ci: add managed Dependabot config (Terraform)

Author: jeisaacs

.github/dependabot.yml

@@ -9,10 +9,14 @@ updates:
     open-pull-requests-limit: 5
     labels:
       - "dependencies"
+    assignees:
+      - "jeisaacs"
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "weekly"
     open-pull-requests-limit: 5
     labels:
       - "dependencies"
+    assignees:
+      - "jeisaacs"