chore(nix): update flakes

[anmonteiro]

alternative to #1099 that fixes nix-ocaml/nix-overlays#1816

[art-w]

Thank you so much for looking into this! I'm afraid the libcurl.so linking error is still present:

$ nix develop --extra-experimental-features nix-command --extra-experimental-features flakes
arthur@host:~/ocaml-cohttp$ dune build
File "cohttp-curl-lwt/test/dune", line 2, characters 7-28:
2 |  (name cohttp_curl_lwt_tests)
           ^^^^^^^^^^^^^^^^^^^^^
/nix/store/bwkb907myixfzzykp21m9iczkhrq5pfy-binutils-2.43.1/bin/ld: /nix/store/ixq7chmml361204anwph16ll2njcf19d-curl-8.11.0/lib/libcurl.so: undefined reference to `SSL_get0_group_name@OPENSSL_3.2.0'
collect2: error: ld returned 1 exit status
File "caml_startup", line 1:
Error: Error during linking (exit code 1)

I'm not sure why your workflow run command nix build -L .#cohttp-curl-lwt fails on the cohttp-lwt-unix tests with "resolution failed: unknown scheme" but I suspect it hasn't pulled everything required by cohttp-lwt-unix, as it otherwise works in the nix develop shell: (if we explicitly avoid building cohttp-curl-lwt)

arthur@host:~/ocaml-cohttp$ dune runtest -p http,cohttp,cohttp-lwt,cohttp-lwt-unix
(...tests pass with no issue...)

[anmonteiro]

@art-w yeah I thought it was an environment issue because of nix develop ... but clearly it isn't.

I'll try openssl things next when I get a moment.

[anmonteiro]

@art-w i just got to the bottom of this and fixed it in nix-ocaml/nix-overlays#1824