Fix owl benchmark type error

Author: moazzammoriani

Makefile

@@ -135,6 +135,7 @@ _opam/%: _opam/opam-init/init.sh ocaml-versions/%.json
 	@{ case "$*" in \
 		*5.0*) opam pin add -n --yes --switch $* sexplib0.v0.15.0 https://github.com/shakthimaan/sexplib0.git#multicore; \
 	esac };
+	opam pin add -n --yes --switch $* dune https://github.com/dra27/dune/archive/2.9.3-5.0.0.tar.gz
 	opam pin add -n --yes --switch $* base https://github.com/kit-ty-kate/base/archive/500-015.tar.gz
 	opam pin add -n --yes --switch $* coq-core https://github.com/ejgallego/coq/archive/refs/tags/multicore-2021-09-29.tar.gz
 	opam pin add -n --yes --switch $* coq-stdlib https://github.com/ejgallego/coq/archive/refs/tags/multicore-2021-09-29.tar.gz

benchmarks/owl/test_owl.ml

@@ -1,7 +1,7 @@
 open Owl
 
-let size = try int_of_string Sys.argv.(1) with _ -> 2048
+let size = 2048
 
-let () = 
+let _ = 
     let a = Mat.sequential size size in 
-    Mat.(a * a)
+    Mat.(a * a);;