Fix missing transitive dependencies in spago.dhall

Author: thomashoneyman

packages.dhall

@@ -1,4 +1,4 @@
 let upstream =
-      https://github.com/purescript/package-sets/releases/download/psc-0.14.0/packages.dhall sha256:710b53c085a18aa1263474659daa0ae15b7a4f453158c4f60ab448a6b3ed494e
+      https://github.com/purescript/package-sets/releases/download/psc-0.14.3-20210722/packages.dhall sha256:1ceb43aa59436bf5601bac45f6f3781c4e1f0e4c2b8458105b018e5ed8c30f8c
 
 in  upstream

spago.dhall

@@ -6,11 +6,12 @@
   , "effect"
   , "either"
   , "exceptions"
+  , "foldable-traversable"
   , "functions"
   , "maybe"
+  , "prelude"
   , "psci-support"
   , "refs"
-  , "transformers"
   ]
 , packages = ./packages.dhall
 , sources = [ "src/**/*.purs", "test/**/*.purs" ]