importing a package before building

what i'm trying to achieve is the ability to import external package before building the unity project.

tried to do this (without sucess):
```
- name: Import SDK
uses: game-ci/unity-test-runner@v2
env:
UNITY_LICENSE: ${{ secrets.UNITY_LICENSE }}
with:
githubToken: ${{ secrets.GITHUB_TOKEN }}
customParameters: -quit -batchmode -importPackage mypackage.unitypackage
```

can one get the unity executable path to run some unity commands such as:
```
- name: Import SDK
run: /opt/unity/Editor/Unity -importPackage mypackage.unitypackage
```