Allow QuickCheck 2.15

See commercialhaskell/stackage#7391

Author: hasufell

os-string.cabal

@@ -89,7 +89,7 @@ test-suite bytestring-tests
     , base
     , bytestring  >=0.11.3.0
     , os-string
-    , QuickCheck  >=2.7      && <2.15
+    , QuickCheck  >=2.7      && <2.16
 
 test-suite encoding-tests
   default-language: Haskell2010
@@ -107,7 +107,7 @@ test-suite encoding-tests
     , bytestring  >=0.11.3.0
     , deepseq
     , os-string
-    , QuickCheck  >=2.7      && <2.15
+    , QuickCheck  >=2.7      && <2.16
     , quickcheck-classes-base ^>=0.6.2
 
 benchmark bench