Set the minimum constraint for ppx_deriving_yaml

Older versions like 0.1.1 exit fail with this error:

```
File "tool/ood-gen/lib/success_story.ml", line 13, characters 12-79:
13 | [@@deriving of_yaml, stable_record ~version:t ~add:[ slug; body_md; body_html ]]
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: Ppxlib.Deriving: 'of_yaml' is not a supported type deriving generator
```

Author: Leonidas-from-XIV

dune-project

@@ -66,7 +66,7 @@
     (>= 1.10.0)))
   olinkcheck
   ; tools/ood-gen
-  ppx_deriving_yaml
+  (ppx_deriving_yaml (>= 0.3))
   ppx_stable
   ezjsonm
   lambdasoup

ocamlorg.opam

@@ -44,7 +44,7 @@ depends: [
   "alcotest" {with-test}
   "mdx" {with-test & >= "1.10.0"}
   "olinkcheck"
-  "ppx_deriving_yaml"
+  "ppx_deriving_yaml" {>= "0.3"}
   "ppx_stable"
   "ezjsonm"
   "lambdasoup"