cpp example on risc0 repository couldn't run correctly.

[mostafamshk]

Hey man. Hope you have a good day.
Firstly I'm sorry to discuss my issue on this repository. I couldn't find a way to contact you directly.
I'm using risc0 and I wanted to be able to run and prove C++ guest code.
I saw you implemented this feature on branch nils/staticlib.
I cloned this branch and tried to run your cpp example by running make -f Makefile in path risc0/examples/cpp.
But I got this error :

error: package `time v0.3.28` cannot be built because it requires rustc 1.67.0 or newer, while the currently active rustc version is 1.66.0-nightly
Either upgrade to rustc 1.67.0 or newer, or use
cargo update -p [email protected] --precise ver
where `ver` is the latest version of `time` supporting rustc 1.66.0-nightly
riscv32-unknown-elf-c++     hello.cpp   -o hello
make: riscv32-unknown-elf-c++: Command not found
make: *** [<builtin>: hello] Error 127

So I tried to install the rustc version (1.71.1+dfsg0ubuntu1-0ubuntu2). But apt
seems not to have this version to install. And I don't know how to install it.
I would appreciate it if you could help me get through this problem.