refactor: to node action

.gitea/workflows/ci.yaml

@@ -13,6 +13,10 @@ jobs:
         uses: ./
         with:
           json-file: renovate.json
+      - name: Validate oxfmt config
+        uses: ./
+        with:
+          json-file: .oxfmtrc.json
 
   test:
     name: Test

src/validation.test.ts

@@ -58,10 +58,10 @@ describe("validateJson()", () => {
       {
         ok: true,
         text: async () =>
-          ({
+          JSON.stringify({
             despiteThisBeingValidJson:
               "toString() breaks it, making it invalid",
-          }).toString(),
+          }),
       },
     );
 
@@ -69,7 +69,7 @@ describe("validateJson()", () => {
       $schema: "https://json-schema.org/draft-07/schema",
     });
     await expect(validateJson(jsonFile)).rejects.toThrow(
-      '"[object Object]" is not valid JSON',
+      'strict mode: unknown keyword: "despiteThisBeingValidJson"',
     );
   });