tools: update extend to 3.0.2

Update extend to 3.0.2 as 3.0.1 is susceptible to a low-severity security issue.

Refs: https://snyk.io/vuln/npm:extend:20180424

Please 👍 here to fast-track.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines