fix(lerna): downgrade Lerna to previous version to fix thread leaking

[ghiscoding]

• upgrading to latest version of Lerna 4.0.0 has a major side effect of NodeJS threads not being disposed after stopping the project
• see Lerna issue #2841

[codecov]

Codecov Report

Merging #281 (99bb71f) into master (c6e9c3e) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #281   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          209       209           
  Lines        12408     12408           
  Branches      4237      4237           
=========================================
  Hits         12408     12408           

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