Migrate to google-cloud-compute package

Drop requirement on discovery API

.github/workflows/ci-workflow.yml

@@ -3,31 +3,6 @@ name: Continuous testing & Linting
 on: [push]
 
 jobs:
-  test36:
-
-    runs-on: ubuntu-20.04
-    strategy:
-      matrix:
-        python-version: [3.6]
-
-    steps:
-    - uses: actions/checkout@v2
-    - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip
-        pip install -e .[dev]
-    - name: Lint with flake8
-      run: |
-        flake8 img_proof
-        flake8 tests --exclude=data
-    - name: Test with pytest
-      run: |
-        pytest --cov=img_proof
-  
   testall:
 
     runs-on: ubuntu-latest