chore: Upgrade to GitHub-native Dependabot

Change Rust crate update to weekly and npm to monthly.

.dependabot/config.yml

@@ -1,8 +0,0 @@
-version: 1
-update_configs:
-  - package_manager: "rust:cargo"
-    directory: "/."
-    update_schedule: "live"
-  - package_manager: "javascript"
-    directory: "web"
-    update_schedule: "weekly"

.github/dependabot.yml

@@ -0,0 +1,12 @@
+version: 2
+updates:
+  - package-ecosystem: cargo
+    directory: "/."
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 10
+  - package-ecosystem: npm
+    directory: "/web"
+    schedule:
+      interval: monthly
+    open-pull-requests-limit: 10