Release bdebstrap 0.1.2

• examples: Install init instead of systemd-sysv
• Check import definition order with isort
• Format Python code with black
• Add test case for black code formatter
• Correct license claim from MIT to ISC
• Fix examples for non-amd64 architectures (fixes #2):
  • Drop architectures from minimal examples
  • Drop mirrors from minimal Ubuntu example
  • Match also vmlinux* in Debian live example
• Update Debian live system example to bullseye