Update configurator-pg to 0.2.0 (better error messages) (#1457)

* Don't indent first line of configuration parser error messages

configurator-pg returns multi-line errors now. Alternatively,
we could indent all the lines.

postgrest.cabal

@@ -52,7 +52,7 @@ library
                     , bytestring                >= 0.10.8 && < 0.11
                     , case-insensitive          >= 1.2 && < 1.3
                     , cassava                   >= 0.4.5 && < 0.6
-                    , configurator-pg           >= 0.1.0.6 && < 0.2
+                    , configurator-pg           >= 0.2 && < 0.3
                     , containers                >= 0.5.7 && < 0.7
                     , contravariant             >= 1.4 && < 1.6
                     , contravariant-extras      >= 0.3.3 && < 0.4