ci: Block all external network calls in tests (no-changelog) (#4930)

* setup nock to prevent tests from making any external requests

* mock all calls to posthog sdk

packages/cli/test/setup.ts

@@ -0,0 +1,6 @@
+import nock from 'nock';
+
+export default async () => {
+	nock.disableNetConnect();
+	nock.enableNetConnect('127.0.0.1');
+};