Remove finch-jackson

[vkostyukov]

It's being extracted in its own project as per #892.

[codecov-io]

Codecov Report

Merging #920 into master will decrease coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master     #920     +/-   ##
=========================================
- Coverage   82.73%   82.63%   -0.1%     
=========================================
  Files          52       51      -1     
  Lines         776      766     -10     
  Branches       28       28             
=========================================
- Hits          642      633      -9     
+ Misses        134      133      -1

Impacted Files	Coverage Δ
core/src/main/scala/io/finch/package.scala	100% <0%> (ø)	⬆️

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