enhancement: extract version numbers from the title as well

[stapelberg]

This isn’t straight-forward because the version number in the title might not have a distinct prefix, i.e. it might not start with “i3 v…”, see i3/i3#1607 for an example.

[nmschulte]

can reference a list of known versions and simple pattern matching to create a decently robust solution
i suspect this is outdated given that i3bot labels missing-version now