Update swagger-parser to fix definition parse bug

While parsing swagger with additionalProperties, not all definitions are
resolved in swagger-parser < 1.0.34.
(swagger-api/swagger-parser#602)
This brings us to the most recent version of swagger-parser on the 1.x
line.

Fixes: guardrail-dev#40

build.sbt

@@ -60,7 +60,7 @@ val codegenSettings = Seq(
   ),
   libraryDependencies ++= testDependencies ++ Seq(
     "org.scalameta" %% "scalameta" % "2.0.1"
-    , "io.swagger" % "swagger-parser" % "1.0.32"
+    , "io.swagger" % "swagger-parser" % "1.0.34"
     , "org.tpolecat" %% "atto-core"  % "0.6.0"
     , "org.typelevel" %% "cats" % catsVersion
   )