Revert "Correct semigroups conditional version bounds (#134)"

This reverts commit 1445edd.

This is wholly unnecessary, since the version number `8.0` is less than
`8.0.x`, as pointed out in
#134 (comment)

Author: RyanGlScott

vector.cabal

@@ -155,7 +155,7 @@ Library
                , primitive >= 0.5.0.1 && < 0.7
                , ghc-prim >= 0.2 && < 0.6
                , deepseq >= 1.1 && < 1.5
-  if impl(ghc < 8.0)
+  if !impl(ghc > 8.0)
     Build-Depends: semigroups >= 0.18 && < 0.19
 
   Ghc-Options: -O2 -Wall