CIF-684 - Upgrade CI environment to Node 10 LTS

[herzog31]

Motivation and Context

I/O Runtime is phasing out nodejs:6 containers and recommends the usage of nodejs:10 containers with the Node 10 LTS version. This change updates the CI container, so that tests are performed in the same environment.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code passes the code style as defined by ESLint.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes and the overall coverage did not decrease.
• All unit tests pass on CircleCi.
• I ran all tests locally and they pass.

[codecov-io]

Codecov Report

Merging #20 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #20   +/-   ##
=======================================
  Coverage   91.42%   91.42%           
=======================================
  Files          17       17           
  Lines         455      455           
=======================================
  Hits          416      416           
  Misses         39       39

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