Upgrade dependency to reduce slug size
Upgrade dependency to reduce slug size

The latest fastboot release removes some extraneous files that were
inflating our slug size. This is the minimal command I found that
bumped the version:

`yarn upgrade fastboot fastboot-app-server`

rust-lang/crates.io,rust-lang/crates.io,rust-lang/crates.io,rust-lang/crates.io