add base-url option

action.yml

@@ -29,6 +29,9 @@ inputs:
   retry-exempt-status-codes:
     description: A comma separated list of status codes that will NOT be retried e.g. "400,500". No effect unless `retries` is set
     default: 400,401,403,404,422 # from https://github.com/octokit/plugin-retry.js/blob/9a2443746c350b3beedec35cf26e197ea318a261/src/index.ts#L14
+  base-url:
+    description: The root of the API URL of the GHES instance to which to connect.
+    required: false
 outputs:
   result:
     description: The return value of the script, stringified with `JSON.stringify`