Removed unneeded hooks

hooks/post_checkout

@@ -1,3 +0,0 @@
-#!/bin/bash
-# downloads a local copy of qemu on docker-hub build machines
-curl -L https://github.com/balena-io/qemu/releases/download/v3.0.0%2Bresin/qemu-3.0.0+resin-arm.tar.gz | tar zxvf - -C . && mv qemu-3.0.0+resin-arm/qemu-arm-static .

hooks/pre_build

@@ -1,4 +0,0 @@
-#!/bin/bash
-# Register qemu-*-static for all supported processors except the 
-# current one, but also remove all registered binfmt_misc before
-docker run --rm --privileged multiarch/qemu-user-static:register --reset