Enable dependabot (rust-lang#2899)

Resolves: rust-lang#2714

Co-authored-by: Ted Kaminski <tedinski@amazon.com>

.github/dependabot.yml

@@ -0,0 +1,21 @@
+# Copyright Kani Contributors
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+
+# https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+
+  - package-ecosystem: "cargo"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    groups:
+      cargo:
+        update-types:
+          - "minor"
+          - "patch"