devel/py3-pytest: unbreak after r441543

<phase: build-depends >

> py36-pytest-3.1.2 depends on package: py36-setuptools_scm>=0 - not found

> py36-pytest-3.1.2 depends on package: /packages/All/py36-setuptools_scm-1.15.5.txz - not found

> USE_PACKAGE_DEPENDS_ONLY set - not building missing dependency from source

• Error code 1

Reported by: pkg-fallout