release of OCaml 5.3.0

[Octachron]

This PR adds the opam package for the newly release OCaml 5.3.0 compiler:
More precisely, it adds the core compiler package

• ocaml-compiler.5.3.0

and its two variants

• ocaml-base-compiler.5.3.0
• ocaml-variants.5.3.0+trunk

completed by the system version

• ocaml-system.5.3.0 (where I have removed the non-windows arch package)

Simultaneously, this PR moves the dev package

• ocaml-variants.5.3.0+trunk to ocaml-variants.5.3.1+trunk

and adds the necessary metapackage

• ocaml.5.3.1

This time, I have included the two related packages

• ocaml-src.5.3.0
• ocaml-manual.5.3

[Octachron]

cc @mseri @shonfeder @raphael-proust

(I am not sure what it the best way to signal new release of the compiler?)

[mseri]

Seems to include the various changes for host- and arch- packages for windows and to unbreak lock files on other systems that we discussed recently. Ping @dra27 to double check

[dra27]

I think this is correct, because opam has been fixed on macOS et al, but we definitely rename ocaml-variants.5.3.0+trunk to ocaml-variants.5.3.1+trunk (rather than leaving an available: false ocaml-variants.5.3.0+trunk), now?

The changes in ocaml-compiler / ocaml-base-compiler / ocaml-variants are as already tested in #27145 - minor tweak to ocaml-system.5.3.0, just to match the proposal in dra27#20 (keeps system compilers consistent with from-source compilers on Windows).

[Octachron]

Concerning the +trunk package, I mostly followed the change in #27100 which removed all not-available opam files. It might makes sense to mark the file as unavailable temporarily?

[raphael-proust]

It might makes sense to mark the file as unavailable temporarily?

the only difference it'd make is that the packages would end up in the archive at the next clean-up

the purpose of the archive is to allow people to restore their setup to a previous state (e.g., they had a binary compiling at some point and they want to have access to the packages that existed at that point)

I don't think we need that for packages which have never eneterd the repo at all, so I suggest we don't add those packages with the false availibility

[Octachron]

Is there anything blocking the merge?

[raphael-proust]

🐫 ‼️

[Octachron]

Thanks !