Package piqi

Failed to find a solution:

no platform:
2025-05-16 17:19.12 [INFO] Solving for ocaml-base-compiler,
                           piqi, constraints ocaml-base-compiler<=5.3.0,
                           piqi=0.6.0 using opam_repository_commit cf409d95af00ff822422bd76b657ed213b661401

2025-05-16 17:19.14 [INFO] base: eliminated all possibilities in 0.63 s

2025-05-16 17:19.14 [INFO] = base =

2025-05-16 17:19.14 [INFO] Can't find all required versions.
Selected: base-threads.base base-unix.base dune.3.18.2 easy-format.1.3.4
          ocaml.5.5.0 ocaml-config.3 ocaml-options-vanilla.1
          ocamlbuild.0.16.1 ocamlfind.1.9.8 topkg.1.0.8 xmlm.1.4.0
          piqi&ocaml-base-compiler ocaml-variants ocaml-base-compiler
          ocaml-base-compiler
- camlp4 -> (problem)
    piqi 0.6.0 requires < 4.02
    Rejected candidates:
      camlp4.5.3: Requires ocaml >= 5.3 & < 5.4
      camlp4.5.2: Requires ocaml >= 5.2 & < 5.3
      camlp4.5.1: Requires ocaml >= 5.1 & < 5.2
      camlp4.5.0: Requires ocaml >= 5.0 & < 5.1~~
      camlp4.4.14+1: Requires ocaml >= 4.14 & < 4.15
      ...
- ocaml-base-compiler -> ocaml-base-compiler.5.3.0
    User requested <= 5.3.0
- ocaml-compiler -> (problem)
    ocaml-base-compiler 5.3.0 requires = 5.3.0
    Rejected candidates:
      ocaml-compiler.5.5: Incompatible with restriction: = 5.3.0
      ocaml-compiler.5.4: Incompatible with restriction: = 5.3.0
      ocaml-compiler.5.3.0: Requires ocaml = 5.3.0
      ocaml-compiler.5.3.0~rc1: Incompatible with restriction: = 5.3.0
      ocaml-compiler.5.3.0~beta2: Incompatible with restriction: = 5.3.0
      ...
- ocaml-variants -> (problem)
    Rejected candidates:
      ocaml-variants.5.5.0+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.4.0+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.3.1+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.3.0+options: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.3.0+BER: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ...
- piqi -> piqi.0.6.0
    User requested = 0.6.0
- ulex -> (problem)
    Rejected candidates:
      ulex.1.2: Requires ocaml < 5.0