Update dune-project dependencies and fix BTF value allocation method in C stubs for newer version of Ocaml

Author: congwang-mk

dune-project

@@ -14,6 +14,8 @@
   ocaml
   dune
   menhir
-  alcotest))
+  alcotest
+  str
+  unix))
 
 (using menhir 2.0) 

src/btf_stubs.c

@@ -57,7 +57,7 @@ static inline struct btf *btf_of_value(value v) {
 
 /* Convert OCaml value to BTF handle */
 static inline value value_of_btf(struct btf *btf) {
-    value v = alloc_custom(&btf_handle_ops, sizeof(struct btf *), 0, 1);
+    value v = caml_alloc_custom(&btf_handle_ops, sizeof(struct btf *), 0, 1);
     *((struct btf **) Data_custom_val(v)) = btf;
     return v;
 }