fix: use proper multi-ecosystem-groups configuration

- Add top-level 'multi-ecosystem-groups' section
- Move schedule to group level for single consolidated schedule
- Add 'patterns: ["*"]' at ecosystem level (required)
- All ecosystems assigned to 'all-dependencies' group
- Results in single monthly PR with updates across all ecosystems

.github/dependabot.yml

@@ -4,52 +4,34 @@
 # https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
 
 version: 2
+
+multi-ecosystem-groups:
+  all-dependencies:
+    schedule:
+      interval: "monthly"
+
 updates:
   - package-ecosystem: "uv"
     directory: "/"
-    schedule:
-      interval: "monthly"
-    groups:
-      all:
-        patterns:
-          - "*"
+    patterns: ["*"]
+    multi-ecosystem-group: "all-dependencies"
   - package-ecosystem: "bun"
     directory: "/"
-    schedule:
-      interval: "monthly"
-    groups:
-      all:
-        patterns:
-          - "*"
+    patterns: ["*"]
+    multi-ecosystem-group: "all-dependencies"
   - package-ecosystem: "github-actions"
     directory: "/"
-    schedule:
-      interval: "monthly"
-    groups:
-      all:
-        patterns:
-          - "*"
+    patterns: ["*"]
+    multi-ecosystem-group: "all-dependencies"
   - package-ecosystem: "docker"
     directory: "/"
-    schedule:
-      interval: "monthly"
-    groups:
-      all:
-        patterns:
-          - "*"
+    patterns: ["*"]
+    multi-ecosystem-group: "all-dependencies"
   - package-ecosystem: "docker-compose"
     directory: "/"
-    schedule:
-      interval: "monthly"
-    groups:
-      all:
-        patterns:
-          - "*"
+    patterns: ["*"]
+    multi-ecosystem-group: "all-dependencies"
   - package-ecosystem: "devcontainers"
     directory: "/"
-    schedule:
-      interval: "monthly"
-    groups:
-      all:
-        patterns:
-          - "*"
+    patterns: ["*"]
+    multi-ecosystem-group: "all-dependencies"