test: add line break at end of file

PR-URL: #56588
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: RafaelGSS

test/fixtures/disable-signal/sigusr1.js

@@ -1,2 +1,2 @@
 console.log('pid is', process.pid);
-setInterval(() => {}, 1000);
+setInterval(() => {}, 1000);