Upgrade to lts@latest

lambda-calculator.cabal

@@ -36,7 +36,7 @@ executable lambda-calculator
   main-is:             Main.hs
   other-modules:       Paths_lambda_calculator
   ghc-options:         -threaded -rtsopts -with-rtsopts=-N
-  build-depends:       base >= 4.9,
+  build-depends:       base >= 4.9 && < 5,
                        lambda-calculator,
                        optparse-applicative >= 0.13,
                        Shellac,
@@ -74,7 +74,7 @@ test-suite lambda-calculus-lint
   type:                exitcode-stdio-1.0
   hs-source-dirs:      test
   main-is:             HLint.hs
-  build-depends:       base <= 5,
+  build-depends:       base < 5,
                        hlint
   ghc-options:         -threaded -rtsopts -with-rtsopts=-N
   default-language:    Haskell2010

stack.yaml

@@ -5,4 +5,4 @@ packages:
 extra-deps:
 - Shellac-0.9.9
 - Shellac-readline-0.9.9
-resolver: lts-8.8
+resolver: lts-8.19