[conf-flint] use os-version for ubuntu

Author: bobot

packages/conf-flint/conf-flint.3.0/opam

@@ -19,7 +19,7 @@ build: [
 ]
 depexts: [
   ["libflint-dev"] {os-family = "debian"}
-  ["libflint-dev"] {os-family = "ubuntu"}
+  ["libflint-dev"] {os-family = "ubuntu" }
   ["flint"] {os = "macos" & os-distribution = "homebrew"}
   ["flint"] {os-distribution = "macports" & os = "macos"}
   ["flint" "flint-devel"] {os-distribution = "centos"}
@@ -31,6 +31,10 @@ depexts: [
   ["flint"] {os-distribution = "nixos"}
   ["flint"] {os-distribution = "arch"}
 ]
+available: [
+   !(os-family = "ubuntu" & os-version < "24.04")
+]
+
 synopsis: "Virtual package relying on a Flint lib system installation"
 description:
   "This package can only install if the Flint lib version 3 is installed on the system."