ci: run tests on OCaml 5.5

Author: anmonteiro

.github/workflows/opam-ci.yml

@@ -26,8 +26,10 @@ jobs:
           - {ocaml-compiler: '4.14.x', os: ubuntu-latest}
           - {ocaml-compiler: 'ocaml-base-compiler.5.3.0', os: ubuntu-latest}
           - {ocaml-compiler: 'ocaml-base-compiler.5.4.0', os: ubuntu-latest}
+          - {ocaml-compiler: 'ocaml-base-compiler.5.5.0~alpha1', os: ubuntu-latest}
           - {ocaml-compiler: 'ocaml-base-compiler.5.4.0', os: macos-15-intel}
           - {ocaml-compiler: 'ocaml-base-compiler.5.4.0', os: macos-latest}
+          - {ocaml-compiler: 'ocaml-base-compiler.5.5.0~alpha1', os: macos-latest}
             # looks like setup-ocaml@v3 can only run actions on windows for
             # OCaml >= 4.13
             # https://github.com/ocaml/setup-ocaml/issues/822#issuecomment-2215525942