Update OCaml test runner image to OCaml 5.4

Dockerfile

@@ -1,19 +1,27 @@
-FROM ocaml/opam:alpine-3.18-ocaml-5.1 AS builder
+# Using the "no flat float array" based image which is OCaml compiled with
+# --disable-flat-float-array. This gives a container smaller image overall
+# but disables OCaml's optimization for float arrays. Does not prevent
+# float arrays from being used.
+FROM docker.io/ocaml/opam:debian-13-ocaml-5.4-no-flat-float-array AS builder
 
-ENV PATH="/home/opam/.opam/5.1/bin:${PATH}"
+ENV PATH="/home/opam/.opam/5.4/bin:${PATH}"
 
 # We purposefully don't combine the opam update and opam install steps
 # to allow the opam update layer to be re-used in the runner image below 
 RUN opam update
 RUN opam install dune ounit2 yojson ezxmlm
 
 WORKDIR /opt/test-runner
+
+# Set owner to opam for the dune commands
+RUN chown -R opam:opam /opt/test-runner
+
 COPY runner/ .
 RUN dune test && dune build
 
-FROM ocaml/opam:alpine-3.18-ocaml-5.1 AS runner
+FROM docker.io/ocaml/opam:debian-13-ocaml-5.4-no-flat-float-array AS runner
 
-ENV PATH="/home/opam/.opam/5.1/bin:${PATH}"
+ENV PATH="/home/opam/.opam/5.4/bin:${PATH}"
 
 RUN opam update
 RUN opam install base dune ounit2 ppx_deriving ppx_sexp_conv qcheck react calendar

tests/example-empty-file/expected_results.json

@@ -1,6 +1,6 @@
 {
   "version": 3,
   "status": "error",
-  "message": "File \"leap.ml\", line 1:\nError: The implementation leap.ml\n       does not match the interface .test.eobjs/byte/leap.cmi: \n       The value `leap_year' is required but not provided\n       File \"leap.mli\", line 1, characters 0-26: Expected declaration\nmake: *** [Makefile:4: test] Error 1",
+  "message": "File \"leap.ml\", line 1:\nError: The implementation leap.ml does not match the interface leap.mli: \n       The value leap_year is required but not provided\n       File \"leap.mli\", line 1, characters 0-26: Expected declaration\nmake: *** [Makefile:4: test] Error 1",
   "tests": null
 }