Cargo.toml: enable LTO for release build
Cargo.toml: enable LTO for release build

Signed-off-by: Alexandru Agache <69826f943dd6ae0c808126caf67f094b6aee96c2@amazon.com>

firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker