grpc-interceptor is listed as a dependency but is only used for testing utilities

[asottile-sentry]

Environment details

N/A - latest

Steps to reproduce

this is the only usage:

python-spanner/google/cloud/spanner_v1/testing/interceptors.py

Line 16 in 131246c

from grpc_interceptor import ClientInterceptor

it should be an optional dependency and not in install_requires:

python-spanner/setup.py

Line 46 in 131246c

"grpc-interceptor >= 0.15.4",

perhaps an extras_require named testing ?

Code example

N/A

Stack trace

N/A