PEP 494 -- Python 3.6 Release Schedule
3.6.15 schedule
3.6.15 final: 2021-09-04
3.6.16 and beyond schedule
Security fixes only, as needed, until 2021-12

PEP 537 -- Python 3.7 Release Schedule
3.7.12 schedule
final: 2021-09-04
3.7.13 and beyond schedule
Security fixes only, as needed, until 2023-06

PEP 596 -- Python 3.9 Release Schedule
Expected:
3.9.7: Monday, 2021-08-30
3.9.8: Monday, 2021-11-01
3.9.9: Monday, 2022-01-03
3.9.10: Monday, 2022-02-28
Final regular bugfix release with binary installers:
3.9.11: Monday, 2022-05-02