Ci add inhouse master versions

[FabianHofmann]

This PR adds a GH action to test the workflow with PyPSA in-house packages installed from their current master.

Checklist

• I tested my contribution locally and it seems to work fine.
• Code and workflow changes are sufficiently documented.
• Changed dependencies are added to envs/environment.yaml.
• Changes in configuration options are added in all of config.default.yaml.
• Changes in configuration options are also documented in doc/configtables/*.csv.
• A release note doc/release_notes.rst is added.

[fneum]

Good idea, but could this not be incorporated in the existing ci.yaml file to reduce code duplication? Something like:

jobs:
  build:
    strategy:
      matrix:
        os:
        - ubuntu-latest
        - macos-latest
        - windows-latest
        inhouse:
        - stable
        - master
        exclude:
        - os: macos-latest
          inhouse: master
        - os: windows-latest
          inhouse: master
    steps:
    [.....]
    # install inhouse packages from master branch with pip
    - name: Install inhouse packages
      run: |
        pip install git+https://github.com/PyPSA/atlite.git@master git+https://github.com/PyPSA/powerplantmatching.git@master git+https://github.com/PyPSA/linopy.git@master
      if: ${{ matrix.inhouse }} == 'master'

[FabianHofmann]

You mean running stable versions + inhouse masters for all systems, both testing the whole workflow? we could do that, but the total run time would higher. I think having one CI with stable versions for all OS and just one with the inhouse masters using ubuntu, is more efficient.

[fneum]

I agree. I edited the suggestion to exclude Mac and Windows.