Release v0.45.4

What's Changed

• chore(config): Support var substitutions for update monitors by @EyeCantCU in #2413
• qemu: always attach serial console for boot diagnostics by @jonjohnsonjr in #2416
• qemu: log VM resources (arch, cpus, memory) before boot by @89luca89 in #2417
• test: strip sed integration test down to just git-checkout by @justinvreeland in #2420

Full Changelog: v0.45.3...v0.45.4