Upgrade agru (v0.1.15 -> v0.1.16)

Rework README instructions a bit (`-v` -> `--mount`, etc.)

Try building without `privileged: true`

Install agru

Fixes #2

Upgrade Alpine base (3.20.3 -> 3.21.0)

Do not mix secrets and settings in Woodpecker CI configuration

Rework Woodpecker CI config

Upgrade Alpine base (3.19.0 -> 3.20.1)

Upgrade Ansible base (3.18.4 -> 3.19.0)

Redo Woodpecker CI pipeline to use woodpeckerci/plugin-docker-buildx