MAINT: pytest deprecation of nose syntax

**Is your feature request related to a problem? Please describe.**
pytest will eventually remove support for nose syntax (ie, `setup` and `teardown`).

**Describe the solution you'd like**
`setup` => `setup_method`
teardown => `teardown_method`

**Describe alternatives you've considered**
😿 

**Additional context**
partially addressed in #126 