Add model release number to validator?

[lopierra]

Apologies if this is already happening - it would be helpful for the LinkML validator to indicate (maybe in the error log?) which release of the model was used for validation.

We need to better track whether a file has been validated and which model version was used, so when we update the model we know which files need to be re-validated.

Along with this, we should also probably have more frequent minor releases of the model!