Update the agent pattern filter in the makeseeds.py script
Summary: Select seeds running the latest major release.
Check the output from your seeds with this filter.
For reference I got 35 peers from my seeder.
Reviewers: #bitcoin_abc, deadalnix, Mengerian
Reviewed By: #bitcoin_abc, Mengerian
Differential Revision: https://reviews.bitcoinabc.org/D4059