run a cargo update to update all dependencies in lock file

[pcone]

This fixes build issues with lexical-core doing arithmetic operations that are invalid on newer versions of rust. (https://github.com/amethyst/amethyst-starter-2d/issues/27)

I'm not super familiar with Rust package management - it's possible an even more robust solution would involve somehow specifying a version for the transitive dependency on lexical-core in cargo.toml, but just updating the lock file seems like enough of a fix anyway.

I've tested this on a windows 10 box and the app opens and renders properly, but haven't tested on mac/linux.

[Robaire]

This also fixes compilation in Ubuntu.