bump dependency to swh.core[db,http] >= 0.0.60

so tests are not broken when next swh.core version is published.

requirements-swh.txt

-swh.core >= 0.0.59
+swh.core[db,http] >= 0.0.60
 swh.model >= 0.0.27
 swh.objstorage >= 0.0.17
 swh.scheduler >= 0.0.39