BLD: update min versions #35732
- [x] closes #35732

Think this travis build will need a restart: https://travis-ci.org/github/pandas-dev/pandas/jobs/718069611

(I no longer seem to have permissions to do so)

```
INTERNALERROR>     self.cov_controller.configure_node(node)
INTERNALERROR>   File "/home/travis/miniconda3/envs/pandas-dev/lib/python3.7/site-packages/pytest_cov/engine.py", line 274, in configure_node
INTERNALERROR>     workerinput(node).update({
INTERNALERROR>   File "/home/travis/miniconda3/envs/pandas-dev/lib/python3.7/site-packages/pytest_cov/compat.py", line 42, in fn
INTERNALERROR>     return getattr(obj, attr, *args)
INTERNALERROR> AttributeError: 'WorkerController' object has no attribute 'slaveinput'
``` Ref: https://github.com/pandas-dev/pandas/issues/35737 for CI failures thanks @VirosaLi 