Use Semantic Versioning

[csegarragonz]

In this PR I move Faasm and its tightly coupled dependencies (faasm/faabric#334, faasm/cpp#120, and faasm/python#30) to use semantic versioning, or SemVer.

Admittedly, Faasm doesn't expose a stable API, and it will never reach a stable version (i.e. >=1.0.0 according to SemVer). Still, SemVer provides some rationale re. when to tag a new version. Whereas until now we had no rationale at all (only whenever we wanted a new container image).

In summary, with SemVer:

• We tag a new minor version (inv git.bump --minor) any time we introduce a new feature.
• We tag a new patch version (inv git.bump --patch) any time we fix a bug.

We are still a bit selective wrt to what is a feature and what is a bug, and it will still be ultimately arbitrary. But at least it provides a bit more order.

In addition, I also move the tasks to bump tracked dependencies to inv git.bump-dep [--faabric,cpp,python,faasmctl], and bump the faasmctl version to fix the Azure integration tests.

[codecov]

Codecov Report

Merging #775 (f74422b) into main (4aa6888) will decrease coverage by 0.03%.
The diff coverage is n/a.

❗ Current head f74422b differs from pull request most recent head c14a964. Consider uploading reports for the commit c14a964 to get more accurate results

@@            Coverage Diff             @@
##             main     #775      +/-   ##
==========================================
- Coverage   67.43%   67.40%   -0.03%     
==========================================
  Files          69       69              
  Lines        7729     7729              
==========================================
- Hits         5212     5210       -2     
- Misses       2517     2519       +2     

see 1 file with indirect coverage changes