Python 3.6 EOL date is 2021-12-23 (in 2 weeks) [0]. There's also PyPI download stats you can check for your package. E.g. requests has ~20% downloads from 3.6 [1], but for your package it might be way lower, so you can base your decision on that.
[0] https://devguide.python.org/#status-of-python-branches
[1] https://pypistats.org/packages/requests (stats for my packages look weird starting November btw, so might need to look at October data)
