postgres:upgrade should not allow major version upgrade attempts

[swrobel]

I just hosed my database image and had to restore from a backup because I attempted to use dokku postgres:upgrade myapp (with no args) to jump from 12.5 to 14.5. Now, I realize I probably should've read the docs first, but still, if major version upgrades via postgres:upgrade aren't allowed, then it shouldn't attempt them, and should perhaps spit out a link to the docs.

[BorisKamp]

I just hosed my database image and had to restore from a backup because I attempted to use dokku postgres:upgrade myapp (with no args) to jump from 12.5 to 14.5. Now, I realize I probably should've read the docs first, but still, if major version upgrades via postgres:upgrade aren't allowed, then it shouldn't attempt them, and should perhaps spit out a link to the docs.

This is still a problem, I just had the same from 15.4 to (I thought) 15.5
It updated to 16.1 ......