Cap OCADml version below 0.5.0

Version 0.5.0 switch to triangular meshes means a small fix is
needed (next version) to feed the faces into OpenSCAD polyhedron.

Author: geoffder

packages/OSCADml/OSCADml.0.2.1/opam

@@ -17,7 +17,7 @@ depends: [
   "ocaml" {>= "4.14.0"}
   "gg" {>= "1.0.0"}
   "cairo2" {>= "0.6.2"}
-  "OCADml" {>= "0.4.0"}
+  "OCADml" {>= "0.4.0" & < "0.5.0"}
   "odoc" {with-doc}
 ]
 build: [