ci: Add schema to release please config

Author: clepski

release-please-config.json

@@ -1,8 +1,9 @@
 {
-    "packages": {
-      ".": {
-        "release-type": "maven",
-        "package-name": "compas-scl-data-service"
-      }
+  "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json",
+  "packages": {
+    ".": {
+      "release-type": "maven",
+      "package-name": "compas-scl-data-service"
     }
-  }
+  }
+}