Remove unused dep

Author: hackwaly

earlybird.opam

@@ -12,7 +12,6 @@ depends: [
   "ppx_deriving" {>= "5.1"}
   "ppx_deriving_yojson" {>= "3.6.1"}
   "menhir" {>= "20201216" & build}
-  "semver2" {>= "1.1.0" & build}
   "menhirLib" {>= "20201216"}
   "ocaml-compiler-libs" {>= "0.12.3"}
   "iter" {>= "1.2.1"}