feat: add gitlab cicd deep dive post

Tasks:

[X] look into an example with the poke-api (returns no timestamps)
[X] write the bulk of the blogpost
[x] confirm the described steps, starting from scratch
[x] try importing the shared grafana dashboard in a fresh instance
[x] update gist with new code
[x] see if the thumbnail can be centered better
- tried it but no. auto-generated title images here have their limits.

hendriknielaender / double-trouble