feat: use semantic versioning

[szkiba]

Semantic versioning is widespread and well-known and has many advantages. It is advisable to switch from the date-based version to the use of the semantic version.

Assuming that k6 and its extensions use semantic versioning, the semantic version of the distribution will be generated as follows:

• if a major version of a module (k6 or extension) is bumped, or a module is removed, the major version will be bumped (potential breaking change)
• if the minor version of any module (k6 or extension) is bumped or a new module is added, the minor version will be bumped (backward compatible feature change)
• otherwise, the patch version will be bumped