Release new npm version to fix security vulnerability

[jdcoldsmith]

Library Affected:
workbox-build

Issue or Feature Request Description:
Could you please publish this package's most recent commit 01cba90 to fix the security vulnerability that it is causing? Thank you!

[jeffposnick]

Yes; I want to get #2992 included in the next release as well, so once that's merged we will.

[jdcoldsmith]

You da man! Thank you!

[jeffposnick]

It's out: https://github.com/GoogleChrome/workbox/releases/tag/v6.4.2