py-flask-flatpages: Build requires py-test-runner.

Missed in 0.7.2 update, caught by bulk build.

Also add py-pygments to test dependencies, and depend on py-flask>1.0
instead of >=1.0 (per setup.cfg).  The latter does not imply a dependency
change within pkgsrc, as py-flask had been >1.0 for 1+ year when this
was actually introduced at py-flask-flatpages 0.7.1.

(kleink)