chore(test): remove unneeded conftest.py (#129)

The only step inside is triggering  warnings on test collection, and
we do not use custom marks yet.

If we do in the future, we can use better marks / scopes.

Signed-off-by: Mike Fiedler <[email protected]>
Co-authored-by: Dustin Ingram <[email protected]>

Author: miketheman