Expected Behavior

Dune would let me choose whether or not I want to write .mli files

Actual Behavior

Dune enables warning 70 ("missing mli") by default

Specifications

• Version of dune (output of dune --version): 2.9.3
• Version of ocaml (output of ocamlc --version): 4.13.1
• Operating system (distribution and version): arch