tests: revert testing against prerelease deps on Python 3.9#213

gcf-merge-on-green[bot] merged 2 commits into

mastergoogleapis/python-datastore:masterfrom

revert-207-206-test-prerelease-deps-on-python-3.9googleapis/python-datastore:revert-207-206-test-prerelease-deps-on-python-3.9Copy head branch name to clipboard