Check max allowed SemVer bump

[ggwpez]

Adds a --max-bump to the prdoc subcommand to restrict the maximal allowed bump kind.
This can then be used for the backport CI, where we only allow up to minor changes.

[ggwpez]

Now that I'm back I can adjust the code myself if you prefer.

Yea please go ahead @Morganamilo.

[ggwpez]

Output now looks like this:

[ggwpez]