fix: require python 3.7+#1284

parthea merged 8 commits intomaingoogleapis/python-bigquery:mainfrom

owl-bot-update-lock-e7bb19d47c13839fe8c147e50e02e8b6cf5da8edd1af8b82208cd6f66cc2829cgoogleapis/python-bigquery:owl-bot-update-lock-e7bb19d47c13839fe8c147e50e02e8b6cf5da8edd1af8b82208cd6f66cc2829cCopy head branch name to clipboard