'nbdev': Package included in requirements of settings.ini but still not properly installing

Hey @eturok might be late to the party but you can try updating the github actions to include graphviz installation step before calling fastai CI. Here is what worked for me

name: CI
on:  [workflow_dispatch, pull_request, push]

jobs:
  test:
    runs-on: ubuntu-latest
    steps: 
    - uses: actions/checkout@v3
    - name: Setup Graphviz
      uses: ts-graphviz/setup-graphviz@v1
    - uses: fastai/workflows/nbdev-ci@master