dh_make_pgxs: Add debian/watch template (with a github pattern).

4 jobs for master in 8 minutes and 14 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #224269
buster
buster

00:04:53

passed #224271
centos7
centos7

00:04:21

passed #224268
sid

00:08:13

passed #224270
stretch
stretch

00:05:12