Ignore `node_modules` when running `pytest`
Ignore `node_modules` when running `pytest`

There are some python files in `node_modules`, and these package
tests shouldn't run when we run `py.test` directly.

CenterForOpenScience/modular-file-renderer,CenterForOpenScience/modular-file-renderer,felliott/modular-file-renderer,CenterForOpenScience/modular-file-renderer,felliott/modular-file-renderer,felliott/modular-file-renderer,felliott/modular-file-renderer,CenterForOpenScience/modular-file-renderer