chore(deps): fix custom renovate (#540)

Author: millotp

renovate.json

@@ -25,7 +25,7 @@
       "fileMatch": [
         "config/openapitools.json"
       ],
-      "matchString": [
+      "matchStrings": [
         "\"version\": \"(?<currentValue>.*?)\","
       ],
       "depNameTemplate": "com.openapitools:openapi-generator-cli",