v0.13.11

This change adds a simple firmware validator for Nerves devices that validate
their firmware the first time it's run. It's optional and the default is to not
use it. This is useful for all Nerves systems that require validation on boot
and is intended to ease the change on the Raspberry Pi "2.0" Nerves systems.

The simple firmware validator only checks that all OTP applications have started
up successfully. If you already have a firmware validator, you can just ignore
this.

If you don't know if you need a firmware validator, you likely don't since your
device boots with the assumption that the firmware will work. If you need to run
fw_validate or Nerves.Runtime.validate_firmware/0 every time you load new
firmware, then you'll want some code to do it automatically and this is an
option.

See the main README.md and Nerves.Runtime.StartupGuard for integration with
your project.

• Changes
  • Add Nerves.Runtime.StartupGuard
  • Fix new Elixir 1.20 warnings