[dune] Fix build of coq_dune in 4.02.3
[dune] Fix build of coq_dune in 4.02.3

Fixes #8431

maximedenes/coq,ppedrot/coq,SkySkimmer/coq,JasonGross/coq,Zimmi48/coq,Zimmi48/coq,coq/coq,Zimmi48/coq,gares/coq,gares/coq,SkySkimmer/coq,Zimmi48/coq,Matafou/coq,silene/coq,gares/coq,ejgallego/coq,gares/coq,ppedrot/coq,gares/coq,maximedenes/coq,coq/coq,coq/coq,ppedrot/coq,ppedrot/coq,maximedenes/coq,coq/coq,JasonGross/coq,ppedrot/coq,ejgallego/coq,SkySkimmer/coq,silene/coq,JasonGross/coq,maximedenes/coq,ejgallego/coq,Matafou/coq,maximedenes/coq,ejgallego/coq,silene/coq,JasonGross/coq,Matafou/coq,SkySkimmer/coq