Steps to bump k3os version

1. Go to the root directory of the repo. Checkout a branch from master and keep the working tree clean.

2. Fill in an appropriate NEW_K3OS_VERSION, then run the following scripts:

# Specify the K3OS version to update
NEW_K3OS_VERSION=v0.19.4-dev.5

# Get changes in the K3OS directory since the last version update
last_k3os_base_commit=$(git log --grep "K3OS base" --pretty=format:"%h"|head -n 1)
k3os_commits=$(git rev-list --reverse ${last_k3os_base_commit}..HEAD -- k3os)

# Prepare the base commit with the upstream K3OS
rm -r k3os
git clone --branch ${NEW_K3OS_VERSION} --single-branch --depth 1 https://github.com/rancher/k3os
rm -rf k3os/.git
git add k3os
git commit -m "K3OS base: Bump to ${NEW_K3OS_VERSION}"

# Pick all changes on the installer side
git cherry-pick $(echo ${k3os_commits})

# Resolve conflicts if there's any
# Build, test, and make any adaptation to the newer version if required

# Submit a PR