Remove string-conv dependency.

protolude.cabal

@@ -71,7 +71,6 @@ library
     transformers     >= 0.4  && < 0.6,
     text             >= 1.2  && <1.3,
     stm              >= 2.4  && <2.5,
-    string-conv      >= 0.1  && <0.2,
     bytestring       >= 0.10 && <0.11
 
   hs-source-dirs:      src

stack.yaml

@@ -2,6 +2,5 @@ resolver: lts-5.10
 packages:
 - '.'
 extra-deps:
-- string-conv-0.1
 flags: {}
 extra-package-dbs: []