fix: let nix not cache bash generated file

[Atry]

Originally, bash generates /dev/fd/63 from "file+file://"<(printf %s "$PWD") and nix caches the file content with TTL 3600 seconds, as a result, if two flake-parts based devenv projects are created under different paths, they would interfere each other's cache for /dev/fd/63, and result in wrong DEVENV_ROOT.

This PR disables the nix file cache to avoid the problem.

[Atry]

Another solution is to create a flag like --override-input devenv-root "https://postman-echo.com/get?devenv-root=$PWD"

https://postman-echo.com is a service to print the request information, for example, given the URL https://postman-echo.com/get?devenv-root=/home/myuser/myproject , we can use builtins.fromJSON to get the query string of devenv-root.