chore: add dependabot

Author: abelaba

.github/dependabot.yml

@@ -0,0 +1,16 @@
+---
+version: 2
+# update once a week, with a 7-day cooldown
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+    cooldown:
+      default-days: 7
+  - package-ecosystem: pre-commit
+    directory: /
+    schedule:
+      interval: weekly
+    cooldown:
+      default-days: 7