Fix missing dev-repo field lint error in alt-ergo-free.2.0.0

Author: jmid

packages/alt-ergo-free/alt-ergo-free.2.0.0/opam

@@ -4,6 +4,7 @@ maintainer: "[email protected]"
 authors: "Alt-Ergo developers"
 license: "Apache-2.0"
 homepage: "http://alt-ergo.ocamlpro.com/"
+dev-repo: "git+https://github.com/OCamlPro/alt-ergo.git"
 bug-reports: "https://github.com/OCamlPro/alt-ergo/issues"
 
 build: