Update makeseeds.py to support 0.25.x
Summary: Update the user agent filter and minimum block height.
Test Plan:
With the file
test_seeds.dump773 BDownload
as test_seeds.dump:
./contrib/seeds/makeseeds.py < test_seeds.dump
Should output the 1.1.1.1 and 4.4.4.4 IPs.
Reviewers: #bitcoin_abc, PiRK
Reviewed By: #bitcoin_abc, PiRK
Differential Revision: https://reviews.bitcoinabc.org/D11049