Fedora-EPEL: python-kombu needs update to >3

[hairmare]

Currently kombu 4.x is available, @radiorabe we have been using kombu 3.x based on a rebuild of the Fedora/25 SRPM successfully for a while. EPEL still has 2.x.

• https://pkgs.org/download/python-kombu
• https://apps.fedoraproject.org/packages/python-kombu
• https://release-monitoring.org/project/3904/
• https://build.opensuse.org/package/show/home:radiorabe:airtime:python-deps/python-kombu