Allow servant-0.18

Author: maksbotan

servant-openapi3.cabal

@@ -80,7 +80,7 @@ library
                      , http-media                >=0.7.1.3  && <0.9
                      , insert-ordered-containers >=0.2.1.0  && <0.3
                      , lens                      >=4.17     && <4.20
-                     , servant                   >=0.17     && <0.18
+                     , servant                   >=0.17     && <0.19
                      , singleton-bool            >=0.1.4    && <0.2
                      , openapi3                  >=3.0.0    && <4.0
                      , text                      >=1.2.3.0  && <1.3