chore: Add dependabot configuration

It will make GitHub send PRs when the github actions or the Ruts crates
have newer versions.

Author: szabgab

.github/dependabot.yml

@@ -0,0 +1,18 @@
+version: 2
+updates:
+  - package-ecosystem: cargo
+    directory: "/"
+    schedule:
+      interval: weekly
+    groups:
+      rust:
+        patterns:
+          - "*"
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: weekly
+    groups:
+      github-actions:
+        patterns:
+          - "*"