Add Git to "build tools" Docker image
Add Git to "build tools" Docker image

We need Git for two things:

- to run `git diff` in the dependency list check on CI

- to figure out the version from current Git commit. This isn't
  necessary on CI, but helpful for local builds

newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat