Update openmodelica-library-testing-action

[AnHeuermann]

Issue

openmodelica-library-testing-action@v0.2.0 broke because of an update of OMPython (v3.6 ==> v4.0.0).

Run OpenModelica/openmodelica-library-testing-action@v0.2.0
conf-NeuralNetwork.json:
[
  {
    "library": "NeuralNetwork",
    "libraryVersion": "2.1.0",
    "referenceFileExtension": "csv",
    "referenceFileNameDelimiter": ".",
    "referenceFiles": "/home/runner/work/NeuralNetwork/NeuralNetwork/ReferenceFiles",
    "loadFileCommands": [
      "loadFile(\"/home/runner/work/NeuralNetwork/NeuralNetwork/NeuralNetwork/package.mo\")"
    ]
  }
]
Error: Error executing Python script test.py
Command failed: python test.py --verbose --branch=stable --noclean  configs/conf-NeuralNetwork.json

Error: Command failed: python test.py --verbose --branch=stable --noclean  configs/conf-NeuralNetwork.json

Changes

• openmodelica-library-testing-action@v0.2.1 was released and tag v0.2 updated to point to it.
• Use v0.2 tag in CI.