Remove 3.9, 3.11-dev and 3.7 test versions Redo testing versions to reduce cpu use: From pypi downloads, 3.8, 3.9 and 3.10 are all in the vicinity of 30% over past 120 days. Test the edges of the range 3.8/3.10. Skip 3.9. Downloads for 3.7 is at 0, don't bother testing. 3.11 is tested, so we don't need to test 3.11-dev. Test 3.6 and 3.12-dev since they are the minimum/maximum version we support.