CI: Update to codecov-action@v2, Python 3.10-dev to 3.10
CI: Update to codecov-action@v2, Python 3.10-dev to 3.10

On February 1, 2022, the codecov-action v1 will be end of life and not longer function. https://github.com/codecov/codecov-action/tree/v2.1.0#%EF%B8%8F--deprecration-of-v1. This commit updates the action to v2.

Also, the Python 3.10-dev tag is replaced with 3.10 since it's in stable release now.
matplotlib/cycler