DO NOT MERGE: Repo: Update to Rust 1.93

[smalis-msft]

Can't merge this until the internal toolchain binary size issue is fixed, but let's see if anything breaks at least.

[Copilot]

Pull request overview

This PR updates the repository’s minimum Rust toolchain to 1.93 and aligns all CI and helper tooling to use that version so the codebase can start validating against the newer compiler.

Changes:

• Bump workspace.package.rust-version in the root and xsync workspaces from 1.91 to 1.93.
• Update the RUSTUP_TOOLCHAIN constant used by flowey/hvlite to 1.93.0.
• Update all Azure DevOps and GitHub Actions workflows that install Rust via rustup to use 1.93.0 as the default toolchain.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Cargo.toml	Raises the workspace rust-version to 1.93 to require the newer compiler across the main workspace.
xsync/Cargo.toml	Raises the xsync workspace rust-version to 1.93 to match the main workspace.
flowey/flowey_lib_hvlite/src/cfg_rustup_version.rs	Updates the RUSTUP_TOOLCHAIN constant from 1.91.1 to 1.93.0 so flowey’s hvlite tooling invokes the new toolchain.
ci-flowey/openvmm-pr.yaml	Updates all Azure DevOps CI steps that install Rust to use --default-toolchain=1.93.0 instead of 1.91.1.
.github/workflows/openvmm-pr.yaml	Updates GitHub Actions PR workflow to install Rust 1.93.0 on Linux and Windows runners.
.github/workflows/openvmm-pr-release.yaml	Updates the PR release workflow to install Rust 1.93.0 on all supported platforms.
.github/workflows/openvmm-docs-pr.yaml	Updates the docs PR workflow to use Rust 1.93.0 for building documentation.
.github/workflows/openvmm-docs-ci.yaml	Updates the docs CI workflow to use Rust 1.93.0 on all runners.
.github/workflows/openvmm-ci.yaml	Updates the main CI workflow to install Rust 1.93.0 everywhere Rust is bootstrapped.

[github-actions]

At least one Petri test failed.