Remove unused imports (with newer protolude)

The changes here are from fixing stack build with LTS 15.8 (GHC 8.8.3)
to be warning-free. Most if not all come from the newer protolude
version, which adds some things like `unwords`.

So to make sure that we don't get unused import warnings with newer
stackage, this both raises the protolude lower bound and removes
these imports.

test/Feature/InsertSpec.hs

@@ -2,7 +2,6 @@ module Feature.InsertSpec where
 
 import qualified Data.Aeson as JSON
 
-import Control.Monad          (replicateM_, void)
 import Data.List              (lookup)
 import Data.Maybe             (fromJust)
 import Network.Wai            (Application)