Add CI/CD pipeline - Githubissues

CI / CD Goals

[x] The pipeline runs on every push (including tests), but containers are only ever pushed on main and PR==false
[x] The software part of this repo (independent of the models) uses semantic versioning
[x] If a git tag is present (and on main without PR) containers are pushed as latest and x.y.z (full tag structure see below)
[x] If no git tag is present (and on main without PR) containers are pushed as as x.y.z-<githash> (full tag structure see below)

semitechnologies/transformers-inference:<model>-<software-version>

The latest released (e.g. 1.3.3) image with the bert-base-uncased model is pushed as
- semitechnologies/transformers-inference:bert-base-uncased
- semitechnologies/transformers-inference:bert-base-uncased-latest
- semitechnologies/transformers-inference:bert-base-uncased-1.3.3
An unreleased preview version with image bert-base-uncased model is pushed as
- semitechnologies/transformers-inference:bert-base-uncased-1.3.2-cf82aa9
Slashes in the model name are replaced with dashes, e.g. for sentence-transformers/msmarco-distilbert-base-v2 the image becomes
- semitechnologies/transformers-inference:sentence-transformers-msmarco-distilbert-base-v2-latest