Use verdaccio on 127.0.0.1 instead of localhost to avoid ipv6 (#7491)

Fix an intermittent bug in the npm publishing script that causes the script to depend on the network configuration of the host. I think what's happening is that when ipv6 is available, sometimes Verdaccio binds [::1]:5783 instead of 127.0.0.1:5783, but npm tries to publish to 127.0.0.1:5783. Explicitly specifying the loopback address 127.0.0.1 fixes this.

e2e/scripts/verdaccio.yaml

@@ -33,3 +33,6 @@ packages:
 # Log settings.
 logs:
   - {type: stdout, format: pretty, level: http}
+
+listen:
+  - 127.0.0.1:4873

scripts/publish-npm.ts

@@ -32,7 +32,7 @@ import * as child_process from 'child_process';
 import {BAZEL_PACKAGES} from './bazel_packages';
 
 const TMP_DIR = '/tmp/tfjs-publish';
-const VERDACCIO_REGISTRY = 'http://localhost:4873';
+const VERDACCIO_REGISTRY = 'http://127.0.0.1:4873';
 const NPM_REGISTRY = 'https://registry.npmjs.org/';
 
 // This script can not publish the tfjs website