Update cats, cats-effect and http4s versions

[janschultecom]

Solves #3

[codecov-io]

Codecov Report

Merging #4 into master will increase coverage by 2.06%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master       #4      +/-   ##
==========================================
+ Coverage   84.52%   86.58%   +2.06%     
==========================================
  Files           4        4              
  Lines          84       82       -2     
==========================================
  Hits           71       71              
+ Misses         13       11       -2

Impacted Files	Coverage Δ
...s/src/main/scala/platypus/http4s/Http4sVault.scala	75.67% <66.66%> (+3.88%)	⬆️

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[rossabaker]

Thanks. Generally looks correct to me. One possible bit of cruft.

[janschultecom]

Can we merge this?

[rossabaker]

I don't have release keys anymore. I would ask on Nelson Gitter about a release if you need one.