mypy: fix working directory for mypy_extra_test_paths.
mypy: fix working directory for mypy_extra_test_paths.

Change-Id: I55f6b414dd6893590231cc929648db90d3ee4161

sqlalchemy/sqlalchemy,j5int/sqlalchemy,zzzeek/sqlalchemy,j5int/sqlalchemy,monetate/sqlalchemy,monetate/sqlalchemy