chore(nix): update flake.lock

[art-w]

I used nix flake update to update the lockfile (but I'm not familiar at all with nix so do tell if this isn't the right command), as PR #1080 is using the latest conduit.7.1.0 which wasn't available before. I'm opening a new PR to investigate why this nix update seems to result in a weird error:

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