release-please: `bump-minor-pre-major` option and breaking changes

from @artek-koltun https://github.com/opiproject/opi-smbios-bridge/commit/2925f0fdd63978acabe55b96c19eb8de0ce47ee5#r126158213

@glimchb  Should we enable `bump-minor-pre-major` option? 
> Should breaking changes before 1.0.0 produce minor bumps? Default false

and start marking breaking changes with `!`?