[pytest] Increase verbosity (sonic-net#1451)

Increase verbosity of pytest to allow for full, non-truncated error messages to appear in CI unit test results in order to help facilitate troubleshooting of unit test failures.

pytest.ini

@@ -1,2 +1,2 @@
 [pytest]
-addopts = --cov-config=.coveragerc --cov --cov-report html --cov-report term --cov-report xml --junitxml=test-results.xml -v
+addopts = --cov-config=.coveragerc --cov --cov-report html --cov-report term --cov-report xml --junitxml=test-results.xml -vv