Bump minimal version of OCaml required

The `no-naked-pointer` flag was present in older OCaml version but there
is no opam package for this variant of the compiler.

Bump the minimal version to OCaml 4.12.

Author: Halbaroth

.github/workflows/build.yml

@@ -19,7 +19,7 @@ jobs:
           - macos-latest
           - ubuntu-latest
         ocaml-compiler:
-          - ocaml-variants.4.08.1+options,ocaml-option-nnp
+          - ocaml-variants.4.12.1+options,ocaml-option-nnp
           - ocaml-variants.4.14.2+options,ocaml-option-nnp
           - 5.3.0
         exclude:

ancient.opam

@@ -23,7 +23,7 @@ homepage: "https://github.com/OCamlPro/ocaml-ancient"
 bug-reports: "https://github.com/OCamlPro/ocaml-ancient/issues"
 depends: [
   "dune" {>= "3.0"}
-  "ocaml" {>= "4.08"}
+  "ocaml" {>= "4.12"}
   "base-nnp"
   "odoc" {with-doc}
 ]

dune-project

@@ -27,5 +27,5 @@ and any process that has read/write access that disk file can map that
 file in and see the structures.")
   (license "LGPL-2.1-or-later WITH OCaml-LGPL-linking-exception")
   (depends
-    (ocaml (>= 4.08))
+    (ocaml (>= 4.12))
     base-nnp))