Enable CircleCI version 2.1

[tovbinm]

Related issues
Our builds on CircleCI have been queueing up.

Describe the proposed solution
Enabled CircleCI version 2.1 + auto cancelation (in CircleCI settings) to allow canceling workflow builds once a newer commit is pushed to a branch

Describe alternatives you've considered
NA

[codecov]

Codecov Report

Merging #353 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #353      +/-   ##
==========================================
- Coverage   86.63%   86.63%   -0.01%     
==========================================
  Files         335      335              
  Lines       10763    10763              
  Branches      344      344              
==========================================
- Hits         9325     9324       -1     
- Misses       1438     1439       +1

Impacted Files	Coverage Δ
.../op/features/types/FeatureTypeSparkConverter.scala	98.23% <0%> (-0.89%)	⬇️

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