Unreasonably large .git folder

[greole]

Currently my .git folder sits at 180mb. Most seems to be from our documentation builds e.g.

5284e24f2a49 1.6MiB Build_PR_221/.doctrees/environment.pickle
I think we should clean this up at some point.

You can use this shell command to explore it.

git rev-list --objects --all |
  git cat-file --batch-check='%(objecttype) %(objectname) %(objectsize) %(rest)' |
  sed -n 's/^blob //p' |
  sort --numeric-sort --key=2 |
  cut -c 1-12,41- |
  $(command -v gnumfmt || echo numfmt) --field=2 --to=iec-i --suffix=B --padding=7 --round=nearest

`