[TF-M] Semantic versioning

Hi,

I would like to continue the discussion on TF-M semantic versioning started on the last tech forum. Currently TF-M uses a loosely defined versioning schema with major and minor versions, following TF-A. There are several calls to switch TF-M to semantic versioning. Here is the reminder of the meaning: (https://semver.org/) v1.2.3 :

1. MAJOR version when you make incompatible API changes, 2. MINOR version when you add functionality in a backwards compatible manner, and 3. PATCH version when you make backwards compatible bug fixes.

This is a good way to go for a mature project but TF-M will overkill from everyday re-versioning because of new patches. It was discussed on the forum and several options were proposed:

1. Do nothing, reasonably bumping up versions on release time only. 2. Use semantic versioning ignoring changes in PATCH by keeping it 0. So upcoming version could be: v1.2.0, next v1.3.0 and nothing in between. 3. Use option 2 but change PATCH when critical code change delivered within release cadence like a security vulnerability fix to let down-stream project relay on a fixed version. 4. Other ideas?

Personally I tend to follow option 3 but looking for the community input.

Thanks, Anton.