Display a warning when using one of the pre-releases of opam 2.3.0

Author: kit-ty-kate

repo

@@ -4,7 +4,10 @@ upstream: "https://github.com/ocaml/opam-repository/tree/master/"
 announce: [
 """
 [WARNING] opam is out-of-date. Please consider updating it (https://opam.ocaml.org/doc/Install.html)
-""" {(opam-version >= "2.1.0~~" & opam-version < "2.1.6") | opam-version < "2.0.10" | (opam-version >= "2.2.0~~" & opam-version < "2.2.1")}
+""" { opam-version < "2.0.10" |
+      (opam-version >= "2.1.0~~" & opam-version < "2.1.6") |
+      (opam-version >= "2.2.0~~" & opam-version < "2.2.1") |
+      (opam-version >= "2.3.0~~" & opam-version < "2.3.0") }
 """
 [INFO] opam 2.1 and 2.2 include many performance and security improvements over 2.0; please consider upgrading (https://opam.ocaml.org/doc/Install.html)
 """ {opam-version >= "2.0.10" & opam-version < "2.1.0~~"}