databases/py-dbt-core: chase devel/py-pathspec update

Widen the version restriction required by the py-dbt-core port --
changes to py-pathspec are non-breaking. Maintainer confirms that
only the port Makefile needs updating, so omitting adding several
patch files as in the original PR here:
https://bugs.freebsd.org/bugzilla/attachment.cgi?id=246997

PR: 246997
Approved by: Pat Maddox (maintainer)