Dynamically create kubectl config

[Jules-7]

Docker workflow (actions) contains a kubectl step, which is necessary to restart API deployment when a new Docker image is built and pushed.

To properly function, kubectl needs a config file:

 - name: Install and configure kubectl
   uses: actions-hub/kubectl@master
   env:
      KUBE_CONFIG: ${{ secrets.KUBE_CONFIG }}

KUBE_CONFIG is a base64 representation of configuration obtained with: az aks get-credentials --resource-group dh-notify-rg --name dh-notify-aks.

Having KUBE_CONFIG hardcoded into secrets is not a problem unless the resource group (dh-notify-rg) or cluster name (dh-notify-aks) change.

In order to avoid having to manually replace the secret (which is not that much work), a step can be added to the workflow to obtain the configuration and update the secret in the repository (for inspiration check this docs https://docs.github.com/en/rest/actions/secrets?apiVersion=2022-11-28).