devenv: remove LD_LIBRARY_PATH hack from running python environment

Flake lock file updates:

• Updated input 'devenv':
    'github:vlaci/devenv/5186fecbe2835ac45018ea4940388f8523bf1624' (2024-10-04)
  → 'github:vlaci/devenv/385d38cfb6872e7f95cae30d94f7fc4afd23fd76' (2024-10-30)

From the related PR[^1] in `devenv`:

Injecting `LD_LIBRARY_PATH` to the Python runtime environment is great
to bypass the need of having to patch non-nix binaries loaded into
that environment, however it breaks down, when Python executes any
other program not compiled for the given Nix system, e.g. a shell
script via `subprocess`.

To work this around, `devenv` will inject a `pth`[^2] file to the virtual
environment it creates, which mangles the `LD_LIBRARY_PATH` variable,
undoing any changes to it made by `devenv` but preserving changes from
other sources.

[^1]: cachix/devenv#1562
[^2]: https://docs.python.org/3/library/site.html