bump base upper bound to <4.19 (#90)

Author: mitchellwrosen

pqueue.cabal

@@ -29,7 +29,7 @@ library
   default-language:
     Haskell2010
   build-depends:
-  { base >= 4.8 && < 4.18
+  { base >= 4.8 && < 4.19
   , deepseq >= 1.3 && < 1.5
   , indexed-traversable >= 0.1 && < 0.2
   }
@@ -70,7 +70,7 @@ test-suite test
   type: exitcode-stdio-1.0
   main-is: PQueueTests.hs
   build-depends:
-  { base >= 4.8 && < 4.18
+  { base >= 4.8 && < 4.19
   , deepseq >= 1.3 && < 1.5
   , tasty
   , tasty-quickcheck