Update packages/cohttp-async/cohttp-async.5.1.0/opam

Author: mseri

packages/cohttp-async/cohttp-async.5.1.0/opam

@@ -29,7 +29,7 @@ depends: [
   "async_unix" {>= "v0.14.0"}
   "async" {>= "v0.14.0"}
   "base" {>= "v0.11.0"}
-  "core" {with-test}
+  "core" {with-test & < "v0.15.0"}
   "core_unix" {>= "v0.14.0"}
   "cohttp" {= version}
   "conduit-async" {>= "1.2.0"}