Schema version -- do formatted version like activerecord

[mcyoung]

Adds in a formatted version number to the schema record similar to how it is done in activerecord which leads to easier to read conflict resolutions.

E.g. converting

DataMigrate::Data.define(version: 20250415225942)

into

DataMigrate::Data.define(version: 2025_04_15_225942)

just like an activerecord schema looks:

ActiveRecord::Schema[7.2].define(version: 2025_04_16_223838) do

[mcyoung]

@ilyakatz just a heads up for a relatively small QoL PR.

[Morozzzko]

Hey, thanks for the contribution!

It feels a bit like one of those bikeshed-friendly things, BUT! That brings consistency with ActiveRecord and modern Rails, so I'm all for it

I'll merge it a bit later, unless someone can say objective reasons why not

[Morozzzko]

Meanwhile, could you please update this test to match?