The setup.sh failure due to old Rust version

[dloranc]

Short overview

I already had Rust installed and during the setup.sh I ran into this issue:

error: failed to compile `git-delta v0.16.5`, intermediate artifacts can be found at `/var/folders/lf/wjmc8r813kq94h9xq5c8dyb00000gn/T/cargo-installOqGSai`

Caused by:
  package `anstream v0.5.0` cannot be built because it requires rustc 1.70.0 or newer, while the currently active rustc version is 1.65.0
  Try re-running cargo install with `--locked`
error: failed to compile `bat v0.23.0`, intermediate artifacts can be found at `/var/folders/lf/wjmc8r813kq94h9xq5c8dyb00000gn/T/cargo-installvgbSkO`

Caused by:
  package `clap v4.4.3` cannot be built because it requires rustc 1.70.0 or newer, while the currently active rustc version is 1.65.0
  Try re-running cargo install with `--locked`
     Summary Successfully installed exa, hwatch! Failed to install git-delta, bat (see error(s) above).
error: some crates failed to install

The script should check the Rust version is 1.70 or newer.

ToDo

• check the Rust version in setup.sh

[qbart]

I think this is rare case, most people don't have rust.

I think comparing versions in shell adds a bit complexity.
Do you think we could reduce the check to "if rust exists" rather than cargo?