Prevent resize from being called with a negative number

[albertov]

Without this patch this error can occur

       *** Failed! (after 2 tests and 8 shrinks):
       Exception while generating shrink-list:
         Test.QuickCheck.resize: negative size
         CallStack (from HasCallStack):
           error, called at src/Test/QuickCheck/Gen.hs:135:22 in QuickCheck-2.14.2-d7ccc9b265479da84d29b38338ff823e03e3d4c8a90b9f8cdb82b74ac9ff037e:Test.QuickCheck.Gen
         CallStack (from -prof):
           Test.QuickCheck.Gen.resize (src/Test/QuickCheck/Gen.hs:(135,1)-(136,42))
           Test.QuickCheck.Gen.CAF (<entire-module>)

A stack trace reveals the call to resize with a negative value to be inside genericArbitrary

*** Exception (reporting due to +RTS -xc): (THUNK_2_0), stack trace: 
  Test.QuickCheck.Gen.resize,
  called from Test.QuickCheck.Gen.CAF
  --> evaluated by: Test.QuickCheck.Gen.resize,
  called from Test.QuickCheck.Gen.sized,
  called from Test.QuickCheck.Gen.scale,
  called from Test.QuickCheck.Gen.frequency,
  called from Test.QuickCheck.Arbitrary.Generic.genericArbitrary,
  called from Mapbox.Style.QuickCheck.arbitrary,
  called from Test.QuickCheck.Property.forAllShrinkBlind,
  called from Test.Hspec.QuickCheck.prop,
  called from Mapbox.TestUtil.laxJsonProp,
  called from Mapbox.StyleSpec.spec,
  called from Test.Hspec.Core.Tree.bimapTree,
  called from Test.Hspec.Core.Tree.bimapForest,
  called from Test.Hspec.Core.Clock.measure,
  called from Control.Concurrent.Async.async,
  called from Test.Hspec.Core.Runner.Eval.runFormatter,
  called from Test.Hspec.Core.Runner.runSpec,
  called from Test.Hspec.Core.Runner.hspec,
  called from Main.main

This patch prevents the error

[ilyakooo0]

Closed in favour of #10