Add missing Log4J dependency due to Scio 0.13.3 bug

[monzalo14]

Fixes #672

[codecov]

Codecov Report

Merging #671 (90bb65a) into master (70c6157) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #671   +/-   ##
=======================================
  Coverage   71.40%   71.40%           
=======================================
  Files          40       40           
  Lines        1710     1710           
  Branches      140      140           
=======================================
  Hits         1221     1221           
  Misses        489      489           

Flag	Coverage Δ
ratatoolCli	3.07% <ø> (ø)
ratatoolCommon	∅ <ø> (?)
ratatoolDiffy	30.80% <ø> (ø)
ratatoolExamples	15.94% <ø> (ø)
ratatoolSampling	62.58% <ø> (ø)
ratatoolScalacheck	81.67% <ø> (ø)
ratatoolShapeless	4.41% <ø> (ø)

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