Change to underscore

Author: tonybaloney

.github/workflows/gh-tests-ci.yml

@@ -26,12 +26,12 @@ jobs:
     - name: Test with pytest
       run: |
         pytest --cache-clear --cov=./azure --cov-report=xml --cov-branch tests
-    - if: matrix.python-version != 3.6
+    - if: matrix.python_version != 3.6
       name: Test with pytest and ujson
       run: |
         python -m pip install .[ujson]
         pytest --cache-clear tests
-    - if: matrix.python-version == 3.9
+    - if: matrix.python_version == 3.9
       name: Codecov
       uses: codecov/codecov-action@v2
       with: