chore: use npm v6.9.0

[bchew]

Description

• update package-lock files
• update travis-ci yml file to use npm v6.9.0

Motivation and Background Context

Does this PR introduce a breaking change?

• Yes
• No

How Has This Been Tested?

Screenshots (if appropriate):

Check-list:

• I have read the Contributing document.
• I've thought about and labelled my PR/commit message appropriately.
• If this PR introduces breaking changes I've described the impact and migration path for existing applications.
• CI is green (coverage, linting, tests).
• I have updated the documentation accordingly.
• I've two LGTMs/Approvals.
• I've fixed or replied to all my code-review comments.
• I've manually tested with a buddy.
• I've squashed my commits into one.

[codecov-io]

Codecov Report

Merging #834 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #834   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          67     67           
  Lines         967    967           
  Branches      209    209           
=====================================
  Hits          967    967

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov-io]

Codecov Report

Merging #834 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #834   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          67     67           
  Lines         967    967           
  Branches      209    209           
=====================================
  Hits          967    967

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ddd7689...89e6495. Read the comment docs.

[pphminions]

LGTM 🍏

[pphminions]

Merging 🚀