test: fix expose gc settings for Mocha in tests

.mocharc.js

@@ -3,7 +3,7 @@
 module.exports = {
   require: ["ts-node/register", "rocha"],
   spec: ["test/unit/*-test.ts", "test/unit/compat/*-test.{ts,js}"],
-  "expose-gc": true,
+  "v8-expose-gc": true,
   "experimental-worker": true,
   recursive: true,
 }