Lock down the compiler and version for the lifetime of a Python release?

[brettcannon]

I'm not aware of a reason to restrict ourselves to a specific compiler and version, but I'm sure @pablogsal will tell me how I'm being naive about this.

[indygreg]

PBS historically adopted the latest LLVM. There have been minimal issues with this. You do need a CI check to verify library dependencies and symbol references don't change just in case. PBS has this.

[emmatyping]

I don't think there's much of a reason to lock this down. Manylinux had to build their own compiler in the alma images IIRC, but other than that I think it is fine (+1 to checking the library dependencies and symbols like PBS does).