Bump base upper bound to 4.15 (#122)

Author: bgamari

haskeline.cabal

@@ -42,7 +42,7 @@ Library
     -- We require ghc>=7.4.1 (base>=4.5) to use the base library encodings, even
     -- though it was implemented in earlier releases, due to GHC bug #5436 which
     -- wasn't fixed until 7.4.1
-    Build-depends: base >=4.9 && < 4.13, containers>=0.4 && < 0.7,
+    Build-depends: base >=4.9 && < 4.15, containers>=0.4 && < 0.7,
                    directory>=1.1 && < 1.4, bytestring>=0.9 && < 0.11,
                    filepath >= 1.2 && < 1.5, transformers >= 0.2 && < 0.6,
                    process >= 1.0 && < 1.7, stm >= 2.4 && < 2.6,