Update cookbook-openapi3.cabal

Author: tchoutri

doc/cookbook/openapi3/openapi3.cabal

@@ -1,5 +1,5 @@
 name:                cookbook-openapi3
-version:             2.1
+version:             2.2
 synopsis:            OpenAPI 3.0 schema generation example
 homepage:            http://docs.servant.dev/
 license:             BSD3
@@ -8,7 +8,6 @@ author:              Servant Contributors
 maintainer:          [email protected]
 build-type:          Simple
 cabal-version:       >=1.10
-tested-with:         GHC==8.6.5, GHC==8.8.3, GHC ==8.10.7
 
 executable cookbook-openapi3
   main-is:             OpenAPI.lhs