Test suite in boltzgen.0.9.2 fails on >=4.13.0 due to an error position diff

Author: jmid

packages/boltzgen/boltzgen.0.9.2/opam

@@ -10,6 +10,7 @@ bug-reports: "https://git.lacl.fr/barbot/boltzgen/-/issues"
 depends: [
   "dune" {>= "2.7"}
   "ocaml" {>= "4.08.0" & < "5.3.0"}
+  "ocaml" {< "4.13.0" & with-test}
   "ocaml-compiler-libs"
   "cmdliner" {>= "1.0.0" & < "2.0.0"}
   "base-unix"