Outdated Rust version causes MSRV compile error

Problem

$ cargo-build-sbf --version
solana-cargo-build-sbf 1.17.0
platform-tools v1.37
rustc 1.68.0

The latest Solana tools(1.17.0) comes with rustc 1.68.0 which is ~5 releases behind the stable Rust release. This causes problems when a crate bumps their MSRV, which was especially prevalent with the 1.14 release given how behind it got from the stable Rust release.

Example of a confusing MSRV error:

error: package `winnow v0.4.4` cannot be built because it requires rustc 1.64.0 or newer, while the currently active rustc version is 1.62.0-dev

Another related issue is the discrepancy between the repo's Rust version and the version which version gets released with the build tools. https://github.com/solana-labs/solana/issues/31960#issuecomment-1668682153 is a good example of how things could go wrong.

Proposed Solution

Update Rust version to the stable Rust version before publishing a new minor Solana release.

Related: https://github.com/solana-labs/rust/pull/85, https://github.com/solana-labs/solana/issues/31528, https://github.com/solana-labs/solana/issues/32361