chore: add submodules to dependabot (#525)

.github/dependabot.yml

@@ -0,0 +1,16 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
+version: 2
+updates:
+  - package-ecosystem: "gitsubmodule"
+    directory: "/"
+    allow:
+      - dependency-name: "*/forge-std"
+      - dependency-name: "*/tnt-core"
+      - dependency-name: "*/eigenlayer-middleware"
+      - dependency-name: "blueprints/incredible-squaring-symbiotic/contracts/lib/core"
+    schedule:
+      interval: "daily"