chore: add Renovate config targeting dev branch with automerge

renovate.json

@@ -0,0 +1,26 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["config:recommended"],
+  "baseBranches": ["dev"],
+  "ignoreDeps": ["dev.flutter.flutter-plugin-loader"],
+  "automerge": true,
+  "automergeType": "pr",
+  "packageRules": [
+    {
+      "matchUpdateTypes": ["major"],
+      "automerge": false
+    },
+    {
+      "matchManagers": ["pub"],
+      "groupName": "Flutter dependencies"
+    },
+    {
+      "matchManagers": ["gomod"],
+      "groupName": "Go dependencies"
+    },
+    {
+      "matchManagers": ["gradle"],
+      "groupName": "Gradle dependencies"
+    }
+  ]
+}