missed v14 to v15

Author: nsdeschenes

integration-tests/fixtures/generate-bundle-stats/nextjs/nextjs-plugin.test.ts

@@ -185,8 +185,8 @@ describe("Generating nextjs stats", () => {
         configFileName: "next",
         format: "esm",
         detectFormat: "esm",
-        version: `v14`,
-        detectVersion: "v14",
+        version: `v15`,
+        detectVersion: "v15",
         file_format: "mjs",
         enableSourceMaps: false,
         overrideOutputPath: `${nextjsApp}/next.config.mjs`,