chore: Add constraint "omd" {<= "1.3.1"}

* Given we rely on (Omd.to_html ~override)

* See also issue ocaml-community/omd#239

Author: erikmd

learn-ocaml-client.opam

@@ -17,7 +17,7 @@ depends: [
   "base" {>= "v0.9.4"}
   "base64"
   "cmdliner"
-  "omd"
+  "omd" {<= "1.3.1"}
   "asak"
   "cohttp" {>= "1.0.0" & < "2.0.0"}
   "cohttp-lwt-unix" {>= "1.0.0" & < "2.0.0"}

learn-ocaml.opam

@@ -46,7 +46,7 @@ depends: [
   "ocp-ocamlres" {>= "0.4"}
   "ocplib-json-typed" {= "0.6"}
   "odoc" {build & >= "1.3.0"}
-  "omd"
+  "omd" {<= "1.3.1"}
   "pprint"
   "ppx_cstruct"
   "ppx_tools"