relax ppxlib constraint (#334)

Author: jchavarri

styled-ppx.opam

@@ -15,7 +15,7 @@ depends: [
   "ocaml-migrate-parsetree" {= "2.4.0"}
   "ocaml" {= "4.14.0"}
   "ppx_deriving" {= "5.2.1"}
-  "ppxlib" {= "0.27.0"}
+  "ppxlib" {>= "0.27.0"}
   "reason" {= "3.8.2"}
   "sedlex" {= "3.0"}
   "ocaml-lsp-server" {dev}