upgrades 11.X.2→11.(X+1).2

We need to make sure that upgrades from 11.X.A to 11.Y.B (for Y >= 3) work seamlessly and automatically.

Practically, the important cases are A=B=1 and A=B=2, with Y=X+1. Although, likely, allowing any natural numbers there will not require any additional code changes.

CI should test that, we'll fix everything that makes these tests fail