Cabal revisions of sequence-formats-1.6.0

Hackage metadata revisions edit the .cabal file after upload; each diff below is one revision.

 cabal-version:      >=1.10 name:               sequence-formats version:            1.6.0+x-revision: 1 license:            GPL-3 license-file:       LICENSE maintainer:         stephan.schiffels@mac.com     testDat/example.plink.bim  library+    build-depends: base <4.15+     exposed-modules:         SequenceFormats.RareAlleleHistogram         SequenceFormats.FreqSum