Update README to state that RUST and Cargo are required

[Cr0n1c]

During the pipx install I ran into

PIP STDERR
----------
  Running command git clone --filter=blob:none --quiet https://github.com/protectai/vulnhuntr.git /private/var/folders/yh/38q3l89546z2_t4szbspkvc00000gp/T/pip-req-build-bhc5k0c5
  error: subprocess-exited-with-error
  
  × Preparing metadata (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> [6 lines of output]
      
      Cargo, the Rust package manager, is not installed or is not on PATH.
      This package requires Rust and Cargo to compile extensions. Install it through
      the system's package manager or via https://rustup.rs/
      
      Checking for Rust toolchain....
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

This fixed the issue for me: https://www.petergirnus.com/blog/rust-macos-how-to-install

[DanMcInerney]

I haven't had this problem, was it due to the fact you were running it with Python 3.13?