chore: add dependabot.yml (#36)

.github/workflows/dependabot.yml

@@ -0,0 +1,29 @@
+version: 2
+updates:
+  # root
+  - package-ecosystem: "npm"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    target-branch: "develop"
+
+  # frontend
+  - package-ecosystem: "npm"
+    directory: "/frontend"
+    schedule:
+      interval: "weekly"
+    target-branch: "develop"
+
+  # backend
+  - package-ecosystem: "npm"
+    directory: "/backend"
+    schedule:
+      interval: "weekly"
+    target-branch: "develop"
+
+  # docs
+  - package-ecosystem: "npm"
+    directory: "/docs"
+    schedule:
+      interval: "weekly"
+    target-branch: "develop"