Proposal: Language version updates

Thank you for taking the time to advocate for samples practice improvements!

### Description

It is unclear to contributors what language version should be supported. I think we should consider the following guidelines:

* Do not update the minimum language version beyond the oldest supported language version. For specific products that support an older version (such as Serverless Runtimes), an older minimum could be considered.
* Do not update the minimum language version to a non-LTS language version, for languages where there is a specific LTS release.

The guideline should also link to per-language official guidance on version support, such as

This proposal is not suggesting adding minimum version indicators or enforcement where not present already.

### Impact

This will create an improved contributor experience, reducing the amount of revisiting the logic.

### Challenge

Negligible, this is mostly about communicating expectations and does not affect code structure.