fix: move extra-files definition to packages

Author: simon511000

.github/workflows/release-please.yml

@@ -16,6 +16,7 @@ jobs:
         id: release
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
+          release-type: node
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v1
         with:

release-please-config.json

@@ -1,11 +1,15 @@
 {
     "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json",
     "release-type": "none",
-    "extra-files": [
-        {
-            "type": "json",
-            "path": "manifest.json",
-            "jsonpath": "$.version"
+    "packages": {
+        ".": {
+            "extra-files": [
+                {
+                    "type": "json",
+                    "path": "manifest.json",
+                    "jsonpath": "$.version"
+                }
+            ]
         }
-    ]
+    }
 }